Can you people help me come up with a prank to do onn my friends?It has to be a good one not a stupid one lol?

My friends pulled a prank on me.It was horrible lol.I was freaking naked in the locker room trying to look for my clothes until i see my friend in the door way of the locker room with them in her hands i did laugh and think it was funny well.....up to the point where i had to try to find some clothes to wear and i started to worry.I didn't want to walk out in the gym naked but thank god she gave me my clothes back before i had to do something embarrassing.Soooooooo what better prank can i do for revenge lol.That's not to horrible but funny and better then the prank she pulled on me?:D