Cloth Swipe
Swipe a person's cloths while they are showering. Put them in an embarasing place such as the showers for people of the opposite sex.

Shoe Polish Prank
Shoe Polish of the appropriate color on the toilet seat.

Knox
Place several packages of "Knox" (clear geletin) in the toilet of someone who will not be around for several days. Looks like water and is harder to detect than the celophane on the lid. For a more instant effect, there is a substance availlable at most magic supply stores called anhydrous sodium poly-acrylate which holds up to 300 times its weight in water. Doesn't take much to turn a toilet solid or someone's drink, or...

Bathroom Candle Prank
Place a candle a little below the seat and off to the side. Methane lights up quite nicely.

Vinegar In Mouthwash
Pour some vinegar inside your victim's mouthwash.

Smile! Your On Bathroom Candid Camera!
Before a group of friends come over, just take a camera into your bathroom and video tape the sink and toilet. As soon as one of your buddies goes to use the toilet, have your other friends gather around the TV, pop in the video you filmed earlier. When your victim comes out of the bathroom he will wonder what everyone is watching and laughing about...he will then see the screen...it will look like he was being videotaped while using the bathroom!!

Pink Bubbles
Take the lid off the cistern of a toilet. This is where the part that control the flushing is located. Then pour in some bubble bath liquid and some pink food coloring. The next person to flush the toilet will get pink bubbles everywhere!

Remove The Toilet Seat
You can physically remove the toilet seat from any bathroom.

Squish! Squish!
Put some sticky and slimy toothpaste on the toilet seat.

Broth Bath
Jam a couple of boullion cubes inside of a shower head. Once water shoots out, your victim will be taking a broth bath.