See, and I agree with OP on this. The only times I've ever said "no homo" with my friends were in a good natured, making fun of ourselves sort of way. None of my friends are homphobic; we've gone skinny dipping, had wrestling matches with naught but boxers, and it's all fun and games. Maybe there are those frat types for whom any expression of male bonding must be prefaced by "no homo" lest they feel their manhood challenged, but it just hasn't been my experience. It's always said as a way to crack a joke, usually at ourselves, rather than to distance ourselves from some perceived homoerotic threat.