Toward the end of "Community" Season 2, Abed told Jeff about how he had worked as an extra on ABC’s "Cougar Town".

Weeks later, "Cougar Town‘s" Laurie and Travis (played by Busy Philipps and Dan Byrd) showed up in the background of a "Community" episode — and two weeks after that, "Cougar Town" viewers glimpsed what ostensibly was Abed’s ill-fated appearance as an extra.


Community Season 2, Episode 24
Cougar Town Season 2, Episode 22

https://tvline.com/lists/weirdest-tv-crossovers-list-video-supernatural-bones/community-cougar-town/