What's the best prank you've ever played on someone?

one time me and my friends took a condom and filled if full of soap and put it on someone's car door handle lol

my friends and i were doing a prank call then bad lucks come we accidentally dialed the fire station and our line on the phone was " help my aunt is in the hospital" and my other friend was loudly crying then we ended the call after a few minutes the phone rang we answered it and the fireman was so mad because we were all laughing thats it the fireman told that they are going to come. but no one come hahaha :D boring?? no its scary because the fman said we will get sued haha

One year for April fools, i set all of the clocks in the house 4 hours forward, and when it was time for my mom to get up, she thought she was late for work. I don't think i've ever seen her move so fast

I turned the lights out in a public rest room while someone was pooping.

I told my little sister that Ellen Degeneres was a guy. She believed me for over a year until my mom told her the truth :P

I called one of friends saying i was lost, confused and my parents kicked me out so I was walking around heaps late "by myelf"... Lol, It was kinda a mean joke, but we laughed it off.

I don't do pranks because I don't like them being done to me, but as long as it is harmless..

My girlfriend and I telling people at work that we had got married, when we had not.

spot 3 differences in these photos

http://members.home.nl/saen/Special/Zoeken.swf