Peek-a-boom

A Peek-A-Boom (also spelled as Peek-a-boom) is a X-Naut-like enemy appearing in Wario Land: Shake It!. First they are invisible. If Wario came closer, it appears wiht smoke. But if wario came too close, it vanishes again, and again with smoke. These enemies throws Bombs to attack Wario. Sometimes, Wario needs these Bombs to solve puzzles to come closer to treasures. It's very hard to shake a Peek-A-Boom, but it is possible.

Trivia

 * It's name is a pun on the phrase Peek-A-Boo and the exploding sound Boom.