Tactless Woman: Charades

Ally (Catherine Tate) arrives at a friend's house party and is introduced to David, a guest who answers her in sign language. Taking his gestures for charades clues, she launches into the game, calling out categories and film titles and urging him to slow down and act out the whole thing. Even after the friend beside him points out that David is deaf, she fires off another film title before the penny drops. Mortified, she stammers through half-finished apologies and asks the friend to pass one on, only to be told to say it herself. Her attempt to sign sorry dissolves into a string of invented mimes that she narrates aloud, and she ends up announcing that she is off to bed, downstairs, as she backs away.

One of six Tactless Woman party sketches in series 2; Wikipedia's episode list names it Tactless Woman - Charades, while the BBC Studios upload calls it Tactless Woman: Deaf. The same episode also included the Age Difference installment.