A barman named Dick had a regular customer, a doctor, who came in each afternoon and had a daiquiri. But he liked a walnut in it to give it a different flavour.
One afternoon Dick saw him come through the door and realised he'd forgotten to buy any walnuts but he did have some hickory nuts; he dropped one in, hoping the doctor wouldn't notice.
But the Doc took one sip and said, "Is this a walnut daiquiri, Dick?"
"It's a hickory daiquiri, Doc."