1.  slam dunk(n = noun.attribute) - something that is a sure to occur; a foregone conclusion; "predicting his success was a slam dunk"
is a kind of certainty, foregone conclusion, sure thing
Derived form verb slam-dunk₁

2.  slam dunk(n = noun.act) - a forceful dunk;
is a kind of dunk, dunk shot, stuff shot
Derived form verb slam-dunk₂

dunk, dunk shot, grand slam, little slam, slam, slam bang, slam dance, slam dancing, slam on, small slam