100: Part 2
30 Rock Season 5 Episode 21 (04/21/11)
Liz takes Tracy to a strip club to try to attempt to get him to go crazy, but the strippers take him too seriously. She has sobered up and tells Dennis to hit the road.
Jack hallucinates an alternate universe version of himself, as well as a past Jack and a future Jack. Tracy and Kenneth decide it would be a good idea for the former to shoot the latter on the roof. Liz and Jack stop that from happening, and then Jack convinces Tracy to go back to TGS.
Even though the writers wrote garbage for th 100th episode, everyone laughed because they piped the gas leak back into the studio.