Ive done virtually all of those. The cruelest prank was very serious if real and I pulled it on a friend Greg in college who I sometimes lifted with and partied with. He was in graduate school to be a pharmacist so he was scared to do anything to mess that up.
After drinking at the campus bars we were stumbling about campus these two girls picked us up, after a racy game of truth or dare he takes one to hookup with her. The other girl was too nervous told me she couldnt and that she was only 16 and in High school. The next morning I was teasing greg that the girl was only 15 and that was against the law and that he would have to register as a sex offender. Just having some fun.
Later that day, just by happenstance my best friend a sheriffs deputy(and never should have had a badge or a gun) worked about hour and half away decides to come visit. So my evil plan became all too apparent, a gift from the devil himself. Afterall, a coupla weeks prior Greg had pulled some pranks and stated he would never be gotten himself.
So about five in the afternoon I talk my buddy into it. He dons his uniform and gunbelt and his silver clipboard. It followed that we went to the Blue house as it was a partyhouse and the front door was gone at that point and I listened at the door. This is a condensed version of the conversation.
My buddy the cop walks, asks "are you Greg ,......"
Greg "Yes, what going on?"
Cop buddy: "Why dont you tell me what happened last night?"
Greg: "Man nothing, nothing happened' his voice was very panicked, at this point his whole ,life is flashing before his eyes.
Cop buddy: 'Oh yeah, how about Zoe and Alicia?" the name of the two highschoolers from the previous night. My buddy now is obviously seeing how serious this was and that the cop has gotten their names.
Greg: " man nothing happened, nothing happened!" even more louder and more nervous.
Cop buddy: Well she's at pullman memorial hospital with her parents having a rape kit done!'
Greg: *stunned silence, no answer"
Cop buddy: "she was only 13!" total ad lib, and I almost lost it outside the door.
Greg: "oh god" he says in a despondent voice.
Now at this point my cop buddy starts to crack up himself and has to cover his mouth.
Greg: " is this some kind of joke"
My buddy immediately retorts in a loud serious voice "SIR, I would NOT call second degree child rape a joke!!"
"NO, NO thats not what Im saying" very shaken by that.
Cop buddy "I just want you to know that this is a practical joke by Bill....."
AT which point I run screaming "I got you, I got you...." and pointing in his face, we're screaming laughing at him but he was still in shock and not going whats happening. It took several minutes for him to calm down and he was like he was sooooo scared that his whole life was over and that he would have to register as a sex offender and how he was thinking of leaving the country. hahahaahaaa!
We often wondered after that, what if we just left after taking a statement w/o telling him it was a joke, whether he would just disappear and would had left the country. Then someday we might run into him ten years later on vacation on a caribbean Island as he was tending bar and tell him "Dude, it was just a joke!" YOU RUINED MY LIFE! was what we pictured him saying.
He said it changed his life and that he was still shaking for two days. He had gotten had and he admitted that, that was a good one. That was the cruelest Ive done, but my pranks are always real elaborate like that.