The Origami Forum

Pretty much looking for something that looks like it holds together well, but easily falls apart for a prank. Things other than the butterfly ball, if possible please!

Swordfish by Katsuhisa Yamada is one: http://w01.tp1.jp/~a150296341/02/02-3-2008-09.html

If you don't have the tail piece far enough forward when you fold the nose in (step 3 of the combined path at the bottom) the pieces will fall right apart.

There is a business card model that is similar to the butterfly ball.
There is also a cube puzzles from Kunihiko Kasahara's book The Art and Wonder of Origami may also work.

any modular origami, with a few modifications, will achieve the desired affect