slappin' d (to something)
Going hard while doing something.
Guy 1: What you doin tonight?
Guy 2: Slappin' d to weights
In this scenario, guy 2 indicates he will be lifting weights intensely tonight.

Guy 1: Anyone tryna slap some d to pow this weekend?
Guy 2: Yeah, let's slap!
In this scenario, guy 1 is asking his friends if anyone wants to hit the slopes for a powder day this weekend. Guy 2 accepts enthusiastically.

slappin' d (to something)