The fwank bank is part of the memory specifically reserved to retain the names of attractive people in order to later look them up on facebook and masterbate over pictures of them.
Ray: Man who was that bird, she was smoking like a bbq, i almost got a boner just looking at her.
Ollie: That was Jenny, she has a rack that would even make Jordan jealous. An you should see her profile picture it made my penis shed a tear.
Ray: Shit mate I'll save that name in my fwank bank for later.