Being related to somebody because you've both had sex with the same person. Related through the pelvic bone.
Timothy: I had sex with Jordan last night!
Kieron: Cool, I had sex with her last week, that makes us pelvic brothers!
Kieron: Cool, I had sex with her last week, that makes us pelvic brothers!
by HunStarRaw March 03, 2011
Jenna: Rob asked me out last night, but I said no
Anna: Why?
Jenna: I'm boy-cotting right now
me time
Anna: Why?
Jenna: I'm boy-cotting right now
me time
by HunStarRaw February 16, 2015