Mxy flies in the air and strikes a pose, the background behind the unknown entity would shift, an explosion of glitter and lights escaping behind his flowing cape. The words he spoke next, specifically his name would form behind him in spectacular fashion.

I'm Mr. Mxyzptlk! Part-time "interdimensional peacekeeper", full-time fifth-dimensional God of Chaos! My hobbies include conning rubes, playing tricks...

He suddenly pops up behind you, leaning on your shoulder.

And, oh yeah, occasionally destroying worlds. Oopsies!