The antonyms for the phrase "spitting up on" would be words that describe actions that are opposite or opposing. Instead of spitting up on someone or something, one might describe actions such as embracing, hugging or cuddling. At the same time, they could also use words like admiring, praising or adoring, rather than "spitting up on" which would usually involve a negative or unpleasant action. This could include the opposite of "spitting up on someone's shoes," which might involve shining one's own shoes, or conversely, complimenting someone's footwear. Ultimately, the antonyms of "spitting up on" imply positive and pleasant experiences or behaviors, rather than the negative and unwanted ones associated with spitting up.