2) the act of entering a state of being covered in human excrement
3) internet phrase to express utter humiliation during an online game
other variations include: having become shat upon, became shat upon, become shit on, will have been shat upon (the grammatically incorrect use of "shatting" is sometimes used in place of "shat" to express a continuing action)
"Oh shit, son, you just became shat upon!"
*Call of Campers; Modern Warfail 3*
"Become shat upon, kid! You just got 360 no-scoped!"