A clever turn on a classic prank. The original prank calls for putting plastic wrap over a toliet bowl so when someone goes to pee, it splashes back. The jelly john, furthers this, instead of using plastic wrap, you fill the toliet bowl with a layer of clear gelatin thus making the prank harder to detect an much harder to deal with.
It can be used as either a noun, or a verb.
Lester was pissed off at his room mate, so he gave him the ol' jelly john.
Pete's jeans were all wet around the knees because someone jelly johned his toliet.
A mystical creature that crosses a jellyfish and a unicorn. The creature is basically a jellyfish with a horn emerging from its soft upper-part. It is known for its ability to make anyone happy even in their worst of moods.