I recently discovered the worst menu in the world. This absolute shocker of a design features folding sections that collapse if you mouse off them.

This means that if you expand one section, and move your pointer over a new section ... a split second later the new section moves as the old section collapses. It's hysterically funny to watch, and amazingly annoying to use, because every time you're ready to click on a new section it jumps tantalizingly out from under the pointer.