Tommy and Lou in “Unfinished Business”

Tommy

[about taking the Chief's daughter on a date] What if she gets interested?

Lou

Well, then you give her the whole: 'Look, I'm a mess, you're so great, and I can't give you what you need. So, I'm gonna have to do the horrible thing and walk away and think about you for the rest of my life, especially when I masturbate.'

Tommy

Yeah the famous Lou end to the relationship line.