Seth MacFarlane is a guy who likes to break taboos in public, and last night’s Family Guy Presents Seth & Alex’s Almost Live Comedy Show was no exception. (Apparently this came as a surprise to Microsoft, which withdrew its sponsorship of the live-action special after viewing the taping.) One of the line-crossiest moments came when MacFarlane and Alex Borstein (the voice of Lois Griffin) did a routine mocking Marlee Matlin’s speaking voice. To wit: Marlee Matlin calls Moviefone! And sings “Poker Face”! Get it? She talks weird…because she’s deaf!

As you can tell, I think this was a fairly dumb gag — offensive to the hearing-impaired, sure, but also just unoriginal. Any third-grader can riff on the kraaaazy way that some hearing-impaired people sound when they talk. There wasn’t much comedic content here beyond that.

At least, not until Marlee Matlin herself walked onstage to join the fun. Matlin shut Borstein right up, did some fat jokes of her own, and even taught the insensitive comedians some very special sign language. I’m not sure that Matlin’s guest appearance actually made those idiotic deaf jokes any funnier, but it did change the way the bit came across. Or did it? Watch the clip below for yourself, then decide: Is this funny or offensive, or both, or neither? Does it matter that Matlin got to mock her mockers?

UPDATE: Matlin talks to EW and says people need to “lighten up.”