Almost as good a line as 'cheese eating surrender monkeys'. Boris Johnson sums up what's wrong with the LibDems:

They are a bunch of euro-loving road-hump
fetishists who are attempting like some defective vacuum cleaner to suck and
blow at the same time; and the worst of it is that if you do vote Lib Dem in
the demented belief that there could ever be such a thing as a Lib Dem
government, you won't get Prime Minister Clegg. You'll get Prime Minister
Gordon Brown, for five more holepunch-hurling years, because the Lib Dems
almost always vote with Labour, and in my years in Parliament I can't
remember a single moment when they opposed a Labour measure to expand state
spending or state control.