Rules:
1. Catch-phrase or a significant/memorable or clue-giving 'line' from a sitcom is provided. Don't make it completely impossible to guess though. Must also state the decade (approx) the sitcom was made.
2. The person who knows it first writes the sitcom name (more detail if desired). That person is then entitled to add a new catch-phrase (see rule 1). Or leave it to someone who wants to.
3. 1 point for each correctly identified.
4. You can't identify your own catch-phrases.
I'll start...
"I know noooothing." (70s)