To corpse

"The difference on this program is that everybody corpses, and there's no one worse than Ricky."

Shaun Williamson (aka "Barry from EastEnders"), commenting on the BBC series Extras

Watching the extras on an Extras DVD (second season), I learned a bit of acting slang. The Oxford English Dictionary traces its history:

corpse, v. Actors' slang. To confuse or 'put out' (an actor) in the performance of his part; to spoil (a scene or piece of acting) by some blunder.

1873 Slang Dict., Corpse, to stick fast in the dialogue; to confuse or put out the actors by making a mistake.

In 1993, the OED expanded the definition:

[2.] b. intr. Of an actor: to forget one's lines; = DRY v. 2 d; to spoil one's performance by being confused or made to laugh by one's colleagues.

1874 HOTTEN Slang Dict., Corpse, to stick fast in the dialogue. 1958 News Chron. 23 May 4/7 There's a new word, too, from drama school. When anyone forgot their lines in the past they had dried. Today, they have 'corpsed'. 1972 A. BENNETT Getting On I. 32 Mrs Brodribb: When Max —. Geoff: Max (He corpses). Mrs Brodribb: (silencing him with a look) — pauses by your doorstep he is not just relieving himself. He is leaving a message. 1987 Observer 8 Feb. 11/2 Gambon said his dying line ('Oh, I am slain') in the mode of a different theatrical grandee every night — a display of 'suicidal nerve', all to get his co-actor to corpse in the dark.

It's the most recent meaning of the word that's relevant to Extras, though here it's the corpsing performer him- or herself who takes the blame for failing to keep a straight face. The short feature The Art of Corpsing features Ricky Gervais and Stephen Merchant and company corpsing — in take after take after take — and talking about corpsing. One realizes, watching these efforts, how much dedicated work goes into what appears to be the most casual, low-key kind of comedic acting.