yes you are right ^_^ it is an Australian Slang Go off like a frog in a sock meaning 1. go crazy, be raging; 2. (of a party, dance party, etc.) be excellent; be successful; fire; 3. (surfing) produce many good riding waves; really pump 4. (of an illegal establishment) be raided by the police http://www.slang-dictionary.org/Go_off_like_a_frog_in_a_sock

Angela should be made an Honorary Aussie!

lol.... the first time I read it i was thinking of 'going off in a sock' in a different way lol

Thank you, that makes sense to the episode, but really it's a funny metaphor.

TO "Go off like a frog in a sock" - Sexual term, meaning that the person goes off... like a frog in a sock - WILD IN BED