Pens, toys and cigars have all been used as booby traps in past conflicts around the world to harm or kill unsuspecting targets.
Using an element of surprise, booby traps are triggered when someone does something seemingly safe — such as, answering a phone.
Warning: This story contains details some readers will find distressing.
These days, using "apparently harmless" objects designed to contain explosive materials is banned under international humanitarian law.
So questions have been raised after thousands of pagers and walkie-talkies exploded across Lebanon this week.
Civilians were among the 37 people killed, and about 3,000 injured, in the attacks.
But whether the devices can be classified as booby traps, and in breach of the laws of war, may be up for debate.
Booby traps regulated, not banned
Hezbollah has blamed Israel for the wave of attacks targeting communications devices used by the Lebanese militant group.
But Israel has not claimed or denied responsibility.
A fake message is believed to have triggered the explosives hidden in thousands of pagers used by Hezbollah members.
Two children were among the 12 people killed when the devices blew up simultaneously in streets and supermarkets.
About 2,800 others were injured.
The following day, at least 25 people were killed and 450 injured when hand-held radios, or walkie-talkies, also blew up.
Lama Fakih, Human Rights Watch's Middle East and North Africa director, said a "prompt and impartial" investigation should be urgently conducted.
Particularly into the use of booby traps, which goes against international law for its impact on civilians.
Ben Saul, United Nations special rapporteur on human rights and counterterrorism, said although booby traps were regulated by international humanitarian law, they were not banned completely.
"There are some circumstances where you can lawfully use them against combatants if it's done in the right way," he told the ABC.
"But there are special protections for civilians against the use of booby traps."
Debate over device modification
A global treaty, which has been signed by more than 100 countries including Israel, bans "the use booby traps or other devices in the form of apparently harmless portable objects that are specifically designed and constructed to contain explosive material".
Professor Saul said the pagers that exploded across southern Lebanon would fall into the category of an object used by civilians.
But there may be debate over whether they were "specifically designed and constructed" with explosives.
The pager bombings appeared to be a complex operation months in the making, with many experts believing Israel infiltrated the supply chain and rigged hundreds of pagers with explosives before they were imported to Lebanon.
A preliminary investigation by Lebanese authorities found that the communication devices were implanted with explosives before arriving in the country, according to a letter sent to the UN Security Council by Lebanon's mission to the United Nations.
The authorities also determined that the pagers and hand-held radios were detonated by sending electronic messages to the devices, according to the letter seen by Reuters.
"There is one very strict view, which is favoured by some militaries, that only if the device is specifically produced as a booby trap that it would be prohibited," Professor Saul said.
But there are other views, which he said were supported in the US law of war manual, that a modified civilian object would still be considered a booby trap.
"The purpose of international humanitarian law is to draw bright lines between fighters and civilians and to protect civilians from the effects of hostilities," Professor Saul said.
"If you could circumvent the prohibition on booby traps by simply modifying a whole lot of ordinary stuff instead of specifically manufacturing it, that just wouldn't serve that humanitarian purpose."
Booby trap or 'targeted object'?
Iran-backed Hezbollah — Lebanon's strongest armed force — has exchanged fire with Israel's military almost daily since October 8, the day after a deadly Hamas-led assault in southern Israel triggered the war in Gaza.
More than 1,200 people were killed, and about 250 were taken hostage, during Hamas's October 7 attacks in the country, Israeli authorities say.
Israel's retaliatory military campaign has so far killed at least more than 40,000 people in Gaza, according to the Gaza health ministry.
Retired Lieutenant Charles Faint, chair for the Study of Special Operations at The Modern War Institute at West Point, said if Israel was behind the explosions in Lebanon this week, it could argue that Hezbollah fighters were "legitimate targets".
And rather than the exploding communications devices being classed as indiscriminate booby traps, they would be "targeted objects".
"From that standpoint, my personal opinion is that this is going to be accepted as something that's as a legitimate tool of war, and under strict scrutiny, it'll survive as not being a booby trap," he said.
"I think a lot is going to be made of it, but I don't think – other than some harshly-worded protest – much is going to be done about it.”
Were the attacks indiscriminate?
International humanitarian law prohibits indiscriminate attacks that "are not directed at a specific military objective".
While the pagers and walkie-talkies were used by Hezbollah members, there was no guarantee of who would be holding the device at the time it was detonated.
"If you use a method of war which is incapable of distinguishing between the civilian and fighter, then you can't launch that attack," Professor Saul said.
"With pagers, it's absolutely impossible to know who was carrying it at the time."
He added that where was also no way to regulate where the devices detonated.
Videos have shown the explosions went off in the middle of markets and streets surrounded civilians.
"So again, that fails a different rule of humanitarian law, which is to verify what the target is before launching it," he said.
Pagers caused 'superfluous injury'
Under international humanitarian law, it is prohibited to use booby traps that cause unnecessary suffering or superfluous injury, Professor Saul said.
"Fighting in war allows you to take fighters off the battlefield by inflicting violence on them," he said.
"But you shouldn't do more than is necessary or justified to remove them from the battlefield."
There are reports that people were blinded when they looked at the message that triggered the explosions.
Dania El Hallak, a healthcare professional at a Beirut hospital, said she was struggling to cope with what she had seen so far.
"I had to remove bandages only to find no eyeballs in place," she told Reuters.
Professor Saul said blinding as a tactic was "absolutely prohibited".
"You would naturally expect that if someone picks up and looks at an exploding pager, then that would carry a high rate of inflicting blindness," he said.
A case in laws of war 'for years to come'
Military analysts say it appears Israel was responding to Hezbollah rocket attacks on northern Israel that have been largely indiscriminate.
Strategist and retired Australian Army Major General Mick Ryan said Hezbollah had shown no distinction between civilians and military targets.
"Israel however, with these pager attacks, has shown that it can respond not only with aerial bombardment but in a more discriminate and imaginative way," he wrote in an analysis of Tuesday's attacks.
There are fears the attacks were a precursor for a larger operation.
Israel's Defence Minister Yoav Gallant said its war in the region is entering a "new phase", hours after announcing Israeli troops would be moved to the north of the country.
Dr Faint said it makes sense that Israel would have responded to Hezbollah's strikes in the north of the country, but what has played out this week was completely unexpected.
"Unprecedented is probably not a strong enough word for this," he said.
"The scale of what they were able to pull off, the imagination, and the effectiveness of it, are going to be things that people study for a long time.
"This is going to be a case study in tradecraft and international law for years and decades to come."
