My favorite parts:
After Spongebob rips off some of Sandy's tree bark, Sandy says, "You're gonna be wearing an iron lung when I'm through with you, Pinhead."
Spongebob hurriedly duct tapes the tree bark back on, and the face he makes afterwards is really cute and funny.
After Spongebob tries to open the frozen lock, his arms fly back and smack Patrick in the face. Patrick: "Ouch!"
And then after, Patrick says, "Here, let me try." (huffs twice) "Open sesame!" "Well, I've done all I can do."
And the scene after they rip off all of Sandy's fur, and it suddenly turns into spring, Patrick's scream as they try to open the door is hilarious.