Alestorm, the band you want when you've decided to have a pirate themed party where all you plan to do is get drunk. Heck, you could even make a drinking game out of it. Take a shot when they mention rum, and when they say beer drink some beer. You'd get plastered about halfway through an album, guaranteed.
These guys have an interesting genre. Depending on who you ask, they are either Folk Metal, Pirate Metal, or (my personal favorite) Beer Metal.
This song is off of their newest album, and it's absolutely amazing. All the piratey stuff they sing about is really amusing to me, and it's good music to listen to while you play games like Assassin's Creed 4, or Sid Meier's Pirates! since it's all pirate based.