1. "Are you kidding me?" Typically used in Great Britian.
2. The catchphrase of Andy Millman's (Ricky Gervais) in the tv-show-within-a-tv-show, "When the Whistle Blows". (from Extras.) Spoken in a high pitch and followed by "Is s/he havin' a laff?"
"What would you go for first if you were a piranha?"
"I'd probably just have a bag of crisps."
"Are you having a laugh?"