Which music group appeared as themselves in season 4 episode 13?

Boyz II Men appeared as themselves in season 4, episode 13 of *The Fresh Prince of Bel-Air*.

The episode, “‘Twas the Night Before Christening,” follows Will’s attempt to arrange a memorable christening for baby Nicky. After boasting that he can provide live entertainment, Will tries to secure Boyz II Men, the Philadelphia-born vocal group. Their appearance connects the episode’s family comedy to one of the biggest R&B acts of the early 1990s.

A common mix-up is treating the group as merely a musical reference because the episode also features a Boyz II Men CD and jokes about Will knowing them from Philadelphia. The group actually appears on screen as itself and performs at Nicky’s christening. Boyz II Men’s name refers to the quartet’s original lineup at the time, although later years brought lineup changes.