Nick Turner and Lee Rubenstein created the show about two friends who, after accidentally sending their landlord into a coma, successfully plead insanity and are sentenced to an asylum.
Posey will play Dr. Krimmens, the head of the mental hospital. Should the show get picked up, her character could become a regular.
Turner and Rubenstein wrote and will executive produce the series whose pilot starts production on Monday. Jeff Tomsic is directing the episode and serves as the series’ show runner.
Whitmer Thomas was also recently cast as a co-lead opposite Turner, a stand-up comic who is also a regular on VH1′s “Best Week Ever.” Rubenstein contributes to “Saturday Night Live’s” “Weekend Update.”
Pilot also stars Johnny Pemberton, Demorge Brown, Joe Urla, Lindsay Ames, Erik Charles Nielsen, Kate Berlant, Eugene Mirman and Jay Oakerson.
Brooke Posch and Cory Stern are overseeing the pilot for Comedy Central.
Parker, who appears in “Grace of Monaco,” also will co-star opposite Eric McCormack in the indie drama “The Architect,” produced by Metallica’s Lars Ulrich.
Posey is repped by CAA and Untitled Entertainment.