Box turtle Puns

My grandfather tells me this every year.

"My father once caught a turtle so he could make turtle soup that night. He put the turtle in a box to bring it home. He first stopped at the bar to see his buddies. His one buddy asks, 'Hey what's in the box?' He replies, 'I caught a turtle, a big one too.' He opens the box to show the turtle and asks his buddy what he thinks. His friend takes one look and says, 'That isn't a turtle.' My father caught a damn rock."