When you have too much sugar. Like when you're drunk on beer, you're "shrunk" on sugar

lil mad is like big mad but the opposite, you mad but not mad to the extent of pullin somthin

shit-faced drunk

To get “drunk” or high, or to be tripping on mushrooms, Drunk + Shrooms =Shrunk

To drink so much alcohol that you dehydrate (through vomiting/urination/night sweats) and look visibly smaller the next day.

"Shrunk" is a drunken mispronounciation of "drunk".