DTF can be used in Two common ways, being either, "down to fuck", or "down to freestyle".
"Hey, you ready
to spit flow?" "yea man I'm totally DTF. Someone drop a beat"
Me: Hey, you goin to the party tonight?
Jake: Uh depends, is there going
to be any girls?
Me: Yea man and yet are all going
to be DTF..