Two workmates decide to share their lunchtime sandwiches. "What have you got today Jack?" asks Jim.
"Cheese and tomato", Jack replies. "What have you got?"
"Crab paste", says Jim. "OK, let's swap. One of mine for one of yours."
Jim takes a bite of cheese and tomato, "Hey Jack, that's really nice! What do you think of mine?"
Jack takes a bite and immediately spits it out, "What the $@%*!# 'ell's that?"
"Like I said, crab paste"
"Where the ****inell did you get that then?"