People would be stumped upon hearing these.

Passing Conversation

"My dad used to have this game with a friend. They embarrassed me endlessly when I was a teen (but that was a bonus)."

"Basically, when they were walking in the street, whenever they were passing someone, they would say things like:"

"Remember, when you pushed your mother-in-law down the stairs...?"

or

"I mean, it wasn't that much drug, usually I carry way more than that!"

or

"Where did you hide the knife after stabbing him?"

"You get the idea, anything absolutely awful as if they were having an entire conversation about drugs, murder, whatever."

"My dad and his friend had the whole hippie look as well, so innocent passersby would quickly cross the street."

– Xiaozhu

Bad Pronunciation

"I mispronounce Famous peoples names constantly then say it correctly randomly so they never know what to expect."

"Billie Eleash, John Legends, Jason Ackles."

– P**syandA**1

Questionable Favor

"When at work, tell someone: I’m going to the bathroom do you need anything?"

– whatislife4

Some pranksters like to set the scene and observe for their viewing pleasure.

Fake Signage

"Buy a set of 'Voice Activated' or 'Motion Activated' stickers from Amazon, and the possibilities are endless."

– beam_me_up_MFer

Hold This

"I'm a huge fan of just handing somebody something without any explanation and walking away."

– saben1te

Hidden April Fool's

"I put a tiny piece of masking tape over my co-worker’s mouse laser on April fool’s day one year, wrote 'April fool’s' on it. He troubleshot every single thing except examining the mouse. He eventually called IT who simply turned the mouse over and pointed it out to him."

– Swedish-Butt-Whistle

Housewarming Gift

"I know someone who always takes an item to a party & leaves it somewhere in the house, ie a trinket/tchotchke."

– visitjacklake

Throwing someone off when they expect something else that's totally different is a classic favorite.

Headscratcher

"I saw someone on Facebook comment on a picture that 'The three of you look great!.' There were 4 people in the picture."

– axehind

Punking The Siblings

"Every year on National Sibling Day, I post about my two great siblings. I have three siblings."

– Gniphe

Shifty Gesture

"When you shake someone's hand, move yours left to right. As they do the traditional up and down, a hilarious circle ensues."

– spinozasrobot

Unfamiliar Driver

"When driving I like to wave at random people as if I knew them. Hilarious to see instant confusion on their faces."

– thattjuliett

This isn't really a prank, per se, but it is a tactic I've used to ward off harassers on the streets of New York city.

Every time I encountered an individual who would pester me as I was walking alone at sundown and either antagonize me or relentlessly hit me up for drugs I never had, I would tell them immediately, "I'm allergic to bananas."

The nonsequitur statement literally paralyzes them as their brain tries to process what it just heard. And in those moments, I manage to gain more time to further the distance.

I have no idea how I came up with that combination of words but it has worked every time.

Maybe even saved my life.