How do you play greenies in golf?

How do you play greenies in golf?
The Greenies Side Game in Golf

On a par-3 hole, you earn a greenie by hitting the green in one stroke.
On a par-4 hole, by hitting the green in two or fewer strokes.
On a par-5 hole, by hitting the green in three or fewer strokes.

The Greenies Side Game in Golf
  1. On a par-3 hole, you earn a greenie by hitting the green in one stroke.
  2. On a par-4 hole, by hitting the green in two or fewer strokes.
  3. On a par-5 hole, by hitting the green in three or fewer strokes.