A prolonged period of work powered (at least in part) by
Red Bull, a caffinated energy drink originally popularized in European bars. Truly rational and organized people do not look forward to riding the bull, though some
procrastinators (me) and
masochists claim it enhances their performance.
As a general standard such a session involves staying up all night (only if one was up during the day) and ingesting at least one can of Red Bull. Projects completed while riding the bull tend to be hacked together and often lack enduring quality.
Usage:
"I'm sorry, but I won't be able to make your party tonight because I've been riding the bull for the previous 37 hours. Next time you see me playing Quake when I should be researching, please kick me."