Chill dudes who partake in the grueling sport of competitive swimming (mostly collegiate though some are chill enough in high school to be considered a Swim Bro.) The aquatic equivalent of a Lax Bro so to speak.

see: Lax Bro
dude 1: "Those Swim Bros stack like 6000 yards a day. Holy shit their ripped."

dude 2: "Yeah man those guys are hardcore."
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Mike: "Whad up fellow swim bro, you ready to hit the poolski and get that 200x30 IM set"

Brendan: "Chyeaa bro lets do it"
by urbanswimmer October 20, 2009
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