I was in the bathroom when someone came up to me and asked me if I wanted to cross swords. He then started to swing his penis at me. That's not koo I said, so to defend myself, I swung my penis back at his. He took much pleasure in crossing swords.
A form of male bonding. When two males share a urinal or toilet bowl during urination, the two males cross their pee streams in a manner to harken to the act of crossing swords in battle. They may even have pee fights where they trade stream hits much like jedi trade lightsaber blows.
In an act of brotherly bonding, Mike and Joe decided to cross swords one day.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).