The B team refers to the "other team", I.E. the team we are not on...... gays. A member of said team would therefore be referred to as a "B teamer", rhyming with "steamer", which has its own definition here.
"Jack went to Bangkok and didn't get laid, I think he's on the B team.""You're right, he must be a B teamer"
The friend/aquaintence that only hangs out with you because you their other friends arent around. B-TeamFriends usually dont invite eachother to sleepovers and such.
Guy: Hey, i dont normally see u with Jessica, do u hang out alot?
Not using your best underwear, but your back up underwear. Usually occurs when you haven't done the laundry in a while, and are in desperate need of clean underwear.