To rat someone out. As in telling the police about a drug deal.
Imma drop a dime on these niggaz.
to throw a nice pass; in basketball terms, an assist
yo check it Bibby just dropped another dime to Vlade!
if you want a gal, sometimes you have to drop a dime on her
To snitch on someone. Often, to save their own ass. Comes from the old cost for a payphone call, ten cents.
"John got popped, so he dropped a dime on his supplier and they let him go."
the act of snitching, ratting, or otherwise disclosing information meant to hurt or discredit someone else. This a play on tips and selling someone out.
"Shit, Tino dropped the dime on me skippin class. Man, I'ma fuck that motherfucker up!"
There were no suspects in the case until someone dropped a dime on the right person!