Chocolate
When this prank arrives at your recipient's door, it looks like a normal shipping tube. Delighted to open a package thinking it's something special, after all, they are a special person. What could it be? A custom Poster? A delicate gift? The shipping tube comes with a "Fragile, this side up" sticker letting them know there's something important inside (the other end is sealed shut for higher effectiveness. This tends to lead to more surprises once it's opened and they are spewed with 1.5 - 4.5 ounces of really annoying glitter that they have to clean up.
A spring loaded glitter bomb, for the a-hole they are. Whether it's a friend, an enemy, a family member or the perfect prank for your annoying neighbor, this is the best prank of all the pranks.
You can hope for glitter on their lap, glitter on their computer, glitter down their pants, wherever it ends up this annoying gag gift leaves glitter everywhere.