Peek-a-boom

A Peek-a-boom is a ninja-like enemy appearing in Wario Land: Shake It! Its name is a pun on the phrase "peek-a-boo" and the exploding sound "boom".

At first, it is invisible. If Wario comes closer, it appears with a cloud of smoke, but if Wario comes too close to them, it vanishes again with more smoke. These enemies throw bombs to attack Wario - up to five can be on the field at a time before the Peek-a-boom ceases fire. Sometimes, Wario needs these bombs to solve puzzles, which let him get to treasures. If Wario uses an Earthshake Punch when he is close to a Peek-a-boom, he can pick it up and shake it.