A male gym enthusiast who is significantly lacking in commonsense, competence and knowledge.
This supposedly alpha-male is one who over compensates for his social inadequacies by focussing on his physcial appearance by means of gym-based exercise regimes.
A gymbo is typically a man who's a bigslut for the gym. His physique often attracts the attention of mostly other men which puts him high up on the bro rank of respect. A gymbo is often equipped with a set of babs, boulder shoulders, and the arms of a silver back gorilla -- yet also low-key a heart of gold. The common gymbo doesn't even skip leg day, making his thighs and ass look exceptionally scrumptious. Don't mess with a gymbo unless you want a Beyonce styled hive of gym monkeys chucking their fresh dookies at you.
Bryce: The way that man is bench pressing 300 is making me question my own sexuality
Chelsea: He's such a gymbo, Bryce. Get over it.
Noah: Nah, only another man can see the raw alure of a bangin' hot gymbo