This still is from 30 Rock season 3 episode #14, "The Funcooker":
30 Rock is known for its attention to detail and its endless pursuit of even minor jokes and sight gags, so I am willing to bet that the face on the cover of this magazine is some crush of Liz's that is mentioned at some point, either in previous or subsequent episodes. (Is it Astronaut Mike Dexter, by any chance?)
So. Can anyone figure out who's on the cover of this magazine? Is it a reference to anything, within or outside of the 30 Rock canon? Bonus points: is this a real issue of Playgirl?