A tsunami can't resist the call of a bog. Whenever a tsunami is headed toward land, a bog will always call out to it, "Hey tsunami, don't you want to hit me with your water? Come this way~"
As you listen to the bog's call you realize it looks just like the Numa (ぬま) Numa guy in your mind. You open your eyes and it's just a bog. You close your eyes, and there he is. The Numa Numa guy.