NPR's guide to the running gags from the show.
The Bluths soak Franklin in ether when they want to knock someone out.
2 episodes feature this joke:
The rape horn bleeps out Buster's words as he is knocked out by an ether soaked Franklin.
G.O.B. soaks Franklin in ether to knock someone out.
Sources: Joke data compiled by Adam Cole / NPR. Episode metadata from The TVDB via a Creative Commons Attribution 3.0 United States (CC BY 3.0 US) license.