A phrase used to describe a female who would appear to show an interest in a man. She could also be described as being "up for it" - although 'up for what' cannot be easily defined.
A female who grabs your buttocks within 5 minutes of meeting you can be described as 'beans on'
This occurs after anal intercourseprecisely at the moment you pull out. The anus will gape open just long enough to lower your testicals inside. If performed properly the anus will close with your testicals inside, and eureka you've performed the beansack