I've been trying for years to come up with a decent joke based on the fact that 'yoghurt' sounds a bit like 'yo, gert' - this is the best I could come up with:
Q: What did Ernest Hemingway say in greeting to a fellow ex-pat in Paris during the twenties, after clocking that she had spilled a dairy product on her jumper in the shape of an expletive?
A: Yoghurt! Rude stain! (Yo, Gertrude Stein)