A young man was staying on a farm with his uncle and aunt for the summer.

One morning the aunt and uncle walked in the kitchen and the young man was drinking an extremely large glass of milk.

The young man said "I took the liberty of milking your cow this morning!"

He then continues and says, "it took me a while to get her started up. She must be old and stubbly."

The uncle says with a confused look, "Um son we don't have a cow. We have a bull!"