A narb is a No Apparent Reason Boner. Narb-sparring is when you constantly get narbs throughout the day, and battle with them to either go away, or constantly hide or cover them up.
Every guy has been through this.
Often happen in inconvenient times, like when you wear shorts or go to a shopping mall.
I was Narb-sparring all yesterday when we were shopping downtown. I swear a few girls noticed, but what can you do except wait it out?