Well seen as everyone above isn't strictly sticking to the 1 liner bit, I love the only fools and horses sketch when they're driving to France:
Rodney: What's your favourite French food Del?
Delboy: Duck a l'orange, I wish I knew how to order it in French.
Rodney: Canard.
Delboy: I know, it's really 'ck n 'ard!
Rodney: No! Duck, it's Canard in French.
Delboy: Oh! Now I just need to know how to say a l'orange in French then.