Stands for "Bank Of Mum And Dad" and refers to people that either choose to or are forced to live, financially speaking, off their parents.
Bloke 1: Mate when I was in the States, I was earning f*ckin 6 bucks an hour AND paying for rent and food. Now I'm home, earning three times that and not paying for shit!
Bloke 2: You moved back in with the folks then, c*unt?
Bloke 1: Yip and not paying board or for anything mate. Just f*ckin freeloading.
Bloke 2: Gotta love the BOMAD mate!