Stevenson set the early action of Treasure Island in western England, so it isn’t surprising they spoke west country English.

Also, a lot of famous pirates (Francis Drake, Richard Greville, Walter Ralegh, et al.) in previous generations had been from those parts. The English west country is dead convenient for the Atlantic and thus the Caribbean, so it’s not surprising to find a lot of seamen from there trying their luck under the black flag.

So, Stevenson set the early action of Treasure Island in the west country of England, so it’s not surprising a lot of them talk a bit broarrrrd then.

But also, a lot of pirates did come out of western England (it was convenient for the Atlantic): Francis Drake, Walter Ralegh, Richard Greville for instance. And up to the later 18th century, the government in London knew it couldn’t trust Devon and Cornwall magistrates to act against pirates, because they were by assumption involved. Arrr!

Every knows it’s the Coast Guard!

Why couldn’t the pirate’s son go to the movie?
Because it was Rrrrrrrrrrrrrrr-rated.

In what chair does a pirate love to sit after a long day of plundering?
His Rrrrrrrrrrrrrrrm chair.

When pirate families go for long vacations, what do the children say that causes the mom and dad pirate to want to have the kids walk the plank?
Rrrrrrrrrrrrrr we there yet?

What branch of the military do pirates like the most?