Here is a good pirate dad joke one-liner. It always make me chuckle:
What did the pirate say on his 80th birthday?
– AYE MATEY!
Get it? Say it out loud if you don´t get it 🙂
It sounds like ‘I’m Eighty’). Yes, absolutely groan-worthy, hahahaha.

Here are some other pirate related dad jokes, while we are at it:
What’s a pirate’s favorite letter?
(They all answer “aRRRRgh”… )
but then say: …nay, a pirate’s true love be for the C.
C is SEA. get it?
A pirate walks and stumbles into a tavern.
The bartender takes one look at him and says: “Hey mate, you know you’ve got a steering wheel stuck down your pants?”
The pirate replies “aye, it be driving me nuts.”
Heheheh. Gotta love it.
Feel free to add a comment or some more pirate dad jokes in the comment section!