I have SNL's "Best of Eddie Murphy" on DVD. There are two sketches in which I heard the number 27.
The first was a Gumby sketch. In this one, Gumby is at a deli and orders a Morey Amsterdam sandwich. But the waiter tells him he still owes $17.27 for the last time he ordered a sandwich. Gumby asks one of his friends to pay the waiter. After his friend pays the money, Gumby again orders the sandwich, but the waiter has no idea what he's talking about. The waiter says that he's worked at the deli for 27 years and has never received an order for a Morey Amsterdam sandwich.
The second was part of a continuing series of "special report" sketches about Buckwheat from "The Little Rascals" being shot. The reporter says that the killer is 27 years old.