spit on (someone or something)
1. To expel saliva or phlegm from one's mouth onto someone or something. I really wish you wouldn't spit on the ground like that—it's really gross! The man spat on me as I walked past.
2. To eject or expel an object from one's mouth onto someone or something. In this usage, a noun or pronoun is used between "spit" and "on." Someone spat their gum on the ground, and it got stuck to the bottom of my sneaker! Make sure you don't talk with your mouth full—you don't want to spit food on your date!
spit (up)on someone or something
1. to eject spit onto someone or something. (Upon is formal and less commonly used than on.) The angry crowd spit on the convict. Don't spit on the sidewalk.
2. to spew spittle onto someone or something while talking. (Upon is formal and less commonly used than on.) I always have a fear of accidentally spitting on someone in the first row while I am talking. I regret spitting on you, but it was an accident.
spit something on(to) something
to expel something from the mouth onto something. You shouldn't spit your gum onto the sidewalk! Don't spit your gum on the pavement.