Often pronounced “fass”
Someone is behaving more maturely than their chronological age or extremely opposite of their normal behavior.
Usually the actions are sexual or
done to entice or attract
attention.
This can can be reflected through clothing, speech patterns and actions.
Often used interchangeably with “grown”
Girl, sit your fast ass down.
Oh you're being fast with that short
skirt showing all those
legs.
We see you over there with
dude! You're so fast.