April Fool!

Yup, today is the day!
Got time for an April Fool gag?
Can't think of any?

Here are a couple of old, old ones that still get a laugh:

Gelitin
Use a gelatin product and place in someone's toilet late at night (you need to give the gelatin some time to harden). Or you could put this in a public toilet somewhere also. Lemon gelatin works well as does clear gelatin.
Once the gelatine hardens, the person who does the business will be surprised when they find their turd rolls sitting on top a solid but wiggly mass inside the toilet.
This is a good gag because no harm is done to anyone's property since the gelatine needs only to be broken up in order to flush, however it may in some cased deprive the family dog of his nightly drink of water.

Or

Cling Wrap
Clearly, one of the top gags is to put clear cling wrap over the toilet bowl and wait to hear your victim scream when they start to wee or poo. This prank has been performed many times at "former" friend's homes, at bus stations, malls, parties and countless other places.The cling wrap needs to be pulled tightly over the toilet bowl and smoothed so there are no wrinkles. When the wee starts to splatter or the poo hits the wrap that's when the victim starts to scream and yell.
Cheers
:beer