To call someone a “bro” is a hyper-heterosexual form of endearment; to pronounce it bra is to increase that sentiment by two- or three-fold. That “bra” is short for brassiere has nothing do to with this venture.
Unlike “bro,” with its implicit whiteness, “brotha” is what black men call each other as a more mild and less committed form of “nigga.” Brotha and bro both stem from brother, and share the same capacities for male friendship in two distinct cultures, namely, black and white.
Gay men figuratively call each other “girl” or “girlfriend,” and when in foul mood, “bitch”—which is also what bro/brotha call their literal gfs when they are unhappy with them. Said gfs, in retaliation, will call their bro/brotha bfs “asshole” or “dick,” which is an interesting pair of words, given that the latter can be inserted into the former during both homosexual and heterosexual coitus.
bf/gf stand for boyfriend/girlfriend—not to be confused with bff, or “best friend forever.” Only females or gay men can be bffs to one another; if a bro/brotha calls another bro/brotha a bff, he will have transgressed a social boundary and immediately be called a “fag,” which in our homophobic world is the opposite of bro.
Less common, but notable, is calling someone “cos,” short for cousin. Both bro and cos invoke genealogy; as one cannot choose their family, one can always choose who they would wish to be family.
“Sis,” “sista,” and “sister” are female counterparts to the bro/brotha paradigm, but not used as much, as females tend to have more complex, if not ambivalent, dynamics with other females. Males and females of any race or sexual orientation can call anyone “bitch.” No one is immune to being called a bitch. That is true democracy.
“Okay, Dad,” or “Okay, Mom” will be said sarcastically if one feels that his friend is being overbearing, didactic, or condescending. In this semantic family of brothers, cousins, and sisters, “mom” and “dad” are never mentioned in good spirit.
Your mom will call you “[something sweet like ‘honey,’ ‘sugar,’ or simply, ‘sweetie’],” and you in turn, ignoring your mom, will call your bf/gf “[something sweet like ‘honey,’ ‘sugar,’ or simply, ‘sweetie’].” “Your mom” is an insult that doesn’t require any more words—the implication being “Your mom [engages in sexually humiliating activity].”
Your dad only wishes that your mom would do to/for him now what she did to/for him a long time ago. I’m referring to anal and/or oral—which fortunately were not exclusive acts, as you’d never have been born, and this world would be one less bro, bitch.