The Metal Pillow Prank
Pranks work best when people don't expect them, and that's why our friend Glennerd's idea is so brilliant: it involves surprising people with a pillow.
It's the last thing they'll be expecting.
Pillows are the least scary things in the world, and when someone lies down on a pillow, that's when they're ready to relax. They aren't ready for a prank!
What you do is take the pillow out of its pillowcase, then wrap it with a single sheet of aluminium foil. (Just one sheet is enough -- too much, and the pillow will look weird.) Then carefully put the pillow and sheet back inside the cover. From the outside, it looks completely normal, but when someone lays down to sleep they're crashing their head through a really loud metal crinkling noise!
It's even better because it's really easy to fix, just take out the foil. They know you got them, but they can't get too upset.