Synonymous to WTF. Replace the "F" word with "cuss", ergo, "what the cuss".
It is an alternative, and less vulgar phrase for WTF.
First heard in the movie "The Fantastic Mr. Fox"
Badger: You're not moving into the tree house.
Mr. Fox: Like "cuss" I'm not.
Badger: The butcher factories nearby are not safe for you to live near.
Mr. Fox: "WTC" are they gonna do? Blow my house down? Chop the tree down to smithereens?
Badger: Fine, we'll set up a meeting with the real estate agent.
Mr. Fox: Don't you ever "cussing" tell me what to do again? Do you "cussing" hear me?
Badger: Yes! I "cussing" hear you now get the "cuss" out of my den!