This article is from the The Complete Guide To Hack Stand-Up Comedy, by Steven Rosenthal and Steve Silberberg (email@example.com) with numerous contributions by others.
Please, please, please, do not do Jack Nicholson. Jack Nicholson is done so
often and people have made fun of those comics who do him so much that even
poking fun of the Nicholson impression is now a cliche'. Just stay away if
you value your dignity.