A popular fight between two entirely different groups. Based on two different internet subcultures, Pirates and Ninjas, as two very different stereotypes battling out to death. May sometimes have robots, cowbows, or ghosts added to it. The phrase is also used as Ninjas vs Pirates.
One Piece Nerd: Pirates would totally win in a battle between Pirates vs Ninjas!
Noun, plural of Pirate of Optimization.
When a group of people come together to do a half-assed job of solving an optimization problem
"Did you see that shitty-assed Pareto of the CHP, Must have been the Pirates of Optimization."
"Yeah, those guys went to Doobie-U"
-Said while looking at the blue line