The act of masturbating in a public restroom, ejaculating into your hand, emerging from the stall, and slapping the nearest person across the face with your jizz hand, declaring "I challenge you to a duel!"
In the name of chivalry, I extended a Gentleman's Challenge towards my urinating opponent.
A competition in which multiple teams of 3 members each compete to see which team can consume a 30 pack of beer, 3 grams of marijuana and a sheet pizza first. This competition is so called because after about an hour after the competition has begun, all teams are so high, drunk and full of pizza that nobody cares about who wins and just end up enjoying each others' company. As gentlemen (and gentlewomen) do.
Philip: "I must say, William. The participants of this year's Gentleman's Challenge are really in the spirit of the competition."
William: "Indeed, sir. It appears no one has given a single fuck about winning since the third blunt was rolled."