pussy shielding

The process by which a female friend or accomplice prevents the potential of sexual intercourse between another female and a male. Often by arousing fears of STDs, pregnancy, or societal scorn (ie "slut").
In summary, The Opposite of Cock Blocking.

Dude, I was trying to get some last night, but Janice's friend totally pussy shielded me.

I'm looking out for my girl, I'm pussy shielding her tonight.

Bitch, stop pussy shielding me, I WANT, to get laid by some dude tonight.