Lucifer Morningstar

You knock on his door, but when he doesn't answer you just open it, walking in on him singing to the Bubble Guppies theme song but with his own words
"Rub-rub-rubber, Duck-duck-duckies!
Rubber, rubber, rubber! Ducky, ducky, duckies! Rubber! Rubber! Ducky! Ducky"

"…Rubber Duckies!"

…