What does whoopty-skippy-do mean?

Solution 1:

As far as I have seen, it is used as a sarcastic cheer. It is used as ‘excellent!’, ‘brilliant!’, ‘genius!’ sarcastically.

Solution 2:

This looks like a one-off extension of whoop, meaning 'hooray' or something similar, and usually used ironically. The OED thinks whoop-de-do [the only form I have ever encountered] means "a fuss, bustle or commotion: a 'to-do' (U.S. colloq.)", but its first citation, The Red Badge of Courage, is " ‘Whoop-a-dadee,’ said a man, ‘here we are! Everybody fightin' ", which fits better with your example than their own definition.

Solution 3:

It's a sarcastic expression of enthusiasm (ie. indicating no enthusiasm whatsoever).

"Whoopty-do" by itself is occasionally used as a genuine expression of enthusiasm, but is usually used sarcastically. "Whooptyd-<intensifier>-do" (typically "whoopty-fucking-do") is invariably sarcastic.