Biggest prank you ever done to someone?

Can't say...It was stupid prank calls we made as spastic teenagers to random numbers...

Ok so I didn't exactly plan this but I went along with it.
I have 3 best friends, and one has the giant mind map she has to do and she always whacks us on the head with it. We all hate it with undying hate. So my other 2 friends decided to do something. One friend took the friend with the map somewhere to get her out of the room. Then my other friend involved with the prank got a big piece of paper and rolled it up to look like her map and replaced it for the real one. Then my friends came back and sat down. Then my one of the friends involved in the prank got up and took the map and walked a bit away from the table. My friend followed her and asked her to give it back but she ripped it and left it on the floor. My friend looked like she was about to cry, it was so funny but sad at the same time. Then my friends were like "hey don't worry this is your mind map! We switched them!" She was pretty upset but understood that she deserved it to some extent.

I made my mom think it was a ghost in her room. Only for a few minutes, though. :o Hehehe. xD

I called a friend and pretended I was a cop, told him his car had been stolen but we had found it. He fell for it hook, line and sinker. lol

Took boss's desk and put on the floor exactly everything he had on top, even kept my job.

You must be very proud of yourself. And it's Domino's, not Dominoes which is a game.

I apologize for the spelling. And no, I am not proud of it now. But back then, I was a College Kid and we all do stupid stuff especially if one also gets pranked by them

I prank called this kid I know multiple times saying I was the step father of the girl he liked and I would beat his ass if he didn't leave her alone. Cruel, but he believed it so hilarious at the time

He must of been scared afterwards. And yea, who hasn't prank called someone... I have when I was in College. I did it once to an old job too, just had to dial *67 first to hide my number though

I hardly do it anymore but I was a nuisance as a young high schooler. Craigslist is the best place to start IMO