Slam dunk
WordNet
noun
(1) A forceful dunk
(2) Something that is a sure to occur; a foregone conclusion
"Predicting his success was a slam dunk"
WiktionaryText
Noun
- An impressively forceful dunk.
- A task expected to present no difficulty.
- As long as you get the vice president's approval first, it'll be a slam dunk.
- Tacking on top of the wind of the following yacht in close quarters