Courtesy of the latest issue of Total Politics, freshly redesigned (ditto its website). As told by Labour's Lord Dubs to TP's Amber Elliott:
Somebody phones up the Lib Dem headquarters and says: "I'd like a copy of the Lib Dem manifesto."
The guy answers, "I'm sorry but we've sold out."
The caller replies, "I know you've sold out, I just want a copy of the manifesto!"
UPDATE: Good gag from Balwal in the comments below (and Unimpressed, you're spot-on). Anyway, keep the political jokes coming . . .