A single girl who is known to their female friends husband as a lesbian for the entertainment and/or benefit of their female friend and themselves. This comes in handy when the husband is leary about his wife going out with her single friends. For some reason it is OK for the wife to go out if the friend is a lesbian. Simply switch out the name chris for your appropriate female friend.
He may think she is a lesbian and doesn't pick up guys, but all the girls know she is simply a chrisbian.