Here's a harmless little prank. Open the shower head and put some Jello mix in there. Tada it's a colorful shower. Shaving cream or vaseline on the ear part of the phone. It helps if you are next door and call so you can hear the prank. Saran wrap on the toilet under the seat. Watch out!
The best prank had me as the victim. Our pledges had to 'kidnap' the sisters. Usually, they would kidnap us at our meeting and have a pizza party or dessert. This year two of our pledges barged into our meeting with a police officer saying that they were being arrested for trying to buy alcohol with fake ID. They were crying,"You can't send me to jail." They made the President, VP (me) and pledge educator go into this room to clear up the whole thing. When we get there, the guy puts on some music and takes off his clothes!
He was a stripper! Wow! I didn't expect that.