As an exclamation:
*Mike just got in a car accident*
Mike, "Shit on my tip!"

As a prepositional phrase:
Jason, "Shit on my tip, that bitch gave me herpes from a blow job."
Kyle, "That sucks, herpes is for life, I know from personal experience."

As a literal representation:
Jason, "Dude I had this girl, doggy style, bent over the toilet, fucking her in the poop cutter."
Erik, "Did you get any shit on your tip?"