I can't take credit for these, "borrowed" them from a mate who posted them on Yahoo Answers.
Addled/ addlepate - foolish, foolish person
Ahoy! - hello
Avast! - Hey
Begad! - By God!
Belay! - Stop that! Shut up!
Bilge/ bilge rat - nonsense talking, insult
Deadlights - yer "eyes", matey!
Dog - insult (e.g., scurvy dog!)
Fair winds! - Good bye, good luck!
Gangway! - out of my way!
Grub - food!
Jack tar/ tar - A sailor.
Lad, lass(ie) - person younger than you
(Land)lubber - insult to someone who is NOT a pirate, arr! Someone who is not a sailor.
Me hearties! - Friends!
Pillage - to rob or raid.
Poxed - insult that someone looks deathly sick.
Rum - drink, or someone acting peculiar. "Ye be a rum fellow for not talking like a Pirate on Pirate's Day!"
Scupper that! - Expression of anger -- I don't know what it means exactly. :)
Scurvy - diseased, insult.
Sea dog - An experienced sea man.
Ship-shape - organized, under control.
Loaded to the Gunwales - drunk :)
Messdeck lawyer - A know-it-all.
Squiffy - buffoon.
Waister - an incompetent sailor.
Shiver me timbers! - Surprise or way to lure someone for sex. "Wanna shiver *me* timbers, mate?"
Sink me! - Surprise.
Swab - A disrespectful term for a seaman. (e.g., "Ye cowardly swabs!")
Walk the plank - fictional term actually from story books. You know what it means...
Wench - female. (e.g., "Ye be a saucy wench!") One who may be promiscuous.
Yo-ho-ho - meaningless, but fun to say!
Aye! - Yes, I agree with all you said and did just now!
Aye aye! - Right away, sir!, when my break is over...
Black Spot - To "place the Black Spot" on another pirate is to sentence him/her to death or warn him of such.
Booty - loot! Gold! Treasure!
Buckaneer, bucko - friend. "Ay, ye be a good bucko!"
Cap'n - Captain.
Doubloon - Spanish gold coin.
Feed the fish - to throw someone overboard dead or alive.
Grog - An alcoholic drink.
Gun - cannon.
Hands - crew of a ship, sailors.
Shark bait - a lazy/worthless sailor.
Splice the mainbrace - To have a drink, or several drinks.
Swag - loot.
Nipperkin - A small drink.