Stop the Q-Tip when there's resistance! | Scattered Quotes

Joey Tribbiani: Go see Frankie. My family's been going to him forever. He did my first suit when I was 15. No, wait, 16. No, excuse me, heh, 15. All right, when was 1990?

Chandler Bing: Okay, you have to stop the Q-Tip when there's resistance!

From Friends – Season 2 Episode 1: ‘The One with Ross’s New Girlfriend’ (2×01) | Produced by NBC

Quote meaning
Chandler is making fun of Joey. The Q-tips are cotton swabs that are used to clean ears. He suggests Joey put one too far and caused himself a brain damage. In other words he’s calling him stupid.