Although I was the asshole in this particular prank, it still stands as a monumental achievement in messing with one’s friends, and I highly recommend trying it out on someone you know. I can’t say they’ll react well, but the moment of realization of the prank should be worth any and all fallout.
Here’s how it works: You have a friend who really, really wants a girlfriend (or a boyfriend, you can pull this on a lady). You and a couple other friends create a fake email account and the necessary social media profiles. Then, for a week or two, lay hints about a fake, highly attractive cousin that’s coming to town (the cousin in mention will have to be attached to the best actor of your friends, with similarly sinister parents). Build it up a little, saying the girl’s perfect for the poor dude at the receiving end of the prank. You’ll see his eyes light up and a little spring in his step. This means you can proceed to the meat of the caper.
Once your friend is obviously interested, have the fake girl seemingly arrive in town. Then, contact the friend as the girl via your own profile, saying, as the girl, you are on your cousin’s computer. Flirt a little. Gain some trust. Then, once it is obvious that the dude is a little suspicious, find a reason to get off the computer. The friend will call you up just to check if he’s being pranked. By this time, you should be in a car or somewhere outside so background noise is somewhere computers don’t go. Sure, smartphones exist now, but this should still be convincing.
At this point, it’ll get challenging. Your friend will try and uncover the truth, saying that there’s no way this girl could exist. Feed his paranoia; be cryptic. Then, contact the poor guy using the new, fake email addresses and profiles. He’ll be happy at first, but then will become more suspicious. That’s when he’ll call the mother or father of the girl’s cousin, a.k.a. your friend who’s good at lying. He won’t be able to ask whether or not the girl exists (that’d be rude), but he’ll still try and weasel the reality from the parents. All they have to do, though, is sound like truthful parents and say how nice the cousin thinks your friend is. Hook, line, and sinker.
Now for the final act. The goal of the prank will reveal itself as not just private humiliation, but public embarrassment. At this stage, the friend will want to meet the cousin. Get “her” to designate a meeting spot. Instead of leaving him out to dry, go for the dramatic route. You’ll need to have had a girl who can be the cousin all along; send her in with the necessary information about him and have the date begin swimmingly. Then, half-way in, the doors of the place will open and who shall storm in? Anyone, really, as long as they can pretend they are madly in love with your friend, call him a bastard, then convince the fake cousin to leave.
The original version never made it to dinner, but the plan was all laid out before the acting friend turned out not to be as good at keeping secrets (but his mom was in on it, so that was funny). Sure, I was the target, but if I know other folks, I know this would work on a friend of yours, so give it a try and enjoy the furious and confused look on some dude’s face for years to come.