From Rap Dictionary
- Pretend to be that which you are not; act tough. You can't front on that -- Beastie Boys (So what'cha want ).
- To bluff or to be a coward.
- To pretend to not be interested; as in "why you frontin' on my boy for?"
- To give something away for a certin amount of time, and get paid back later. (Yo, front me a dime bag..)