TV Trope: Significant Reference Date

Troy: I am mad at you.
Abed: You said you weren’t. We never lie.
Troy: I know.
Abed: We made a deal. October 15th, 2009, ‘friends don’t lie to each other’.
Troy: I know. 

* * *

Troy: From now on, Abed, friends don’t mess with each other. OK?
Abed: Cool.
Troy: Cool. 
[Episode air date: October 15, 2009]

(3.12 Contemporary Impressionists, 1.05 Advanced Criminal Law)