To 'Blow Your Beans' or 'Blowing Your Beans' refers to the act of achieving orgasm or 'cumming'. Generally it is a term used for the male orgasm. However women have been known to use the term too.
Billy - I was goosing my bird last night and she wouldn't let me finish inside her. So I pulled out and she said you can BLOW YOUR BEANS all over my tits.
de Stevie Vodka 7 juin 2011