Everything in "Legend of Duh Bigfoot". The highlight, though, was when Doc was banging his chest ah la Tarzan in order to get the Trio to embrace their wild side. When he asked them to do the same...they leapt at him and banged on his chest. This Troper almost died laughing.
In the episode "Ghostfather" we get this:
Casper: What are you guys gonna do?
Stretch: What we shoulda done in the movie. *he, Stinkie and Fatso take out weapons, ready to kill Doc and Kat*