You can get this achievement in act 2 on the level "A Hard Axe To Follow". It is a boss fight level.
During the first phase of the boss, he will shoot projectiles at you and you just need to keep avoiding them until he gets to his second phase.
In his second phase he will whip out his axe and then do a series of ground attacks until he gets stuck in the ground. Once his axe gets stuck just spit on him (Hold
) and the achievement should unlock.
Here is a quick video guide if you are still having trouble: