A joke goes wrong in three parts

A seahorse walks into a bar.

Part 1

“Why the long face?” asks the barman.

“Don’t be a twat,” replies the seahorse.

Part 2

“How did you walk into the bar? You’re aquatic,” says the barman.

“I’ll f*cking show you aquatic,” shouts the seahorse, and stabs him.

Part 3

“Let’s go over this one more time. Why did you stab him?” asks the policeman.

“I’m not saying anything else until my lawyer gets here,” states the seahorse.