In the sport of triathlon, it describes a competitor who's conversation has become boring due to their incessant talk about the sport, past or upcoming events, training, diet and all things related to triathlons.
We had dinner with Steve yesterday, he's looking great but all he talked about the whole night was triathlon.
A gay who wears mocassins at all time, loves an iPhone 4 with the Doodle Jump app, masturbates to stuffo, and loves Asian-Americans. Also inspires and worships Zach Galifianakis.
Person 1: Hey girl, did you hear about the new kid in school? I think he's from Cacapoopoopeepeeshire.
Person 2: Yea, there's a rumor going around school that he's a "Trinon"?!