Ok, so like, I am not a prescriptivist, blah blah blah, but I do tell people how to use apostrophes for a living, so I found this momentarily funny.
CP[2.sg BE.pres.sg shit[ADJ]] (a clause with a second person subject, the copula and an adjectival complement)and
NP[2sg.poss shit[NOUN]] (a noun phrase consisting of a possessive second person determiner and a noun).Methinks they are not. They just don't know how to spell the right version of two homophonous but otherwise distinct forms.
That's how to kill a joke.