Shoop da Woop is said whenever something awesome happens as a way to condone that what was done is awesome. It can also be used as a magic word to transform. These two can often be confused, so definition one shouldn't be used by someone who commonly uses definition two.
Guy: Cardinals got a touchdown!
Dude: Shoop Da Woop!
Clark Kent: Oh no! An evildoer! I must transform into my superman costume. Shoop Da Woop!