The drunkest person at the bar/party/family dinner. Encourages everyone around them to drink more, often ordering rounds of shots and not paying for them.
Jane: Did you see her puking all over the bartender?
John: Yeah, she's CaptainRidiculous every weekend.
adj. - Unbelievable. Often used to describe that which is beyond the scope of human comparison.
1: I think they should have named that biography "Lance Armstrong: Fucking Ridiculous."
2: No shit. You know who else is fucking ridiculous? Carl Johnson (of San Andreas fame).