mixing metaphors

थूकना: The depiction of disdain. As the heroes of yesteryear Bollywood used to say ‘थूकता हूँ मैं ऐसी नौकरी पर।’
चाटना: Flattery, or obsequious ingratiation. But unlike थूकना, the use of चाटना is best avoided in polite company as the two pertain to different ends of the alimentary canal.
थूक कर चाटना: To go back on one’s words.
We observe here how two metaphors combine to give us a third metaphor. Clearly, literary addition is not the literal adding up of individual meanings.
Unless you’re Shatrughan Sinha trying to cozy up to the PM.