its basically means..you got caught cheating and was foolish to do it so near your locality of where you live..
"i shitted on your own doorstep"-i was in my local bar and who walks in only my nextdoor neighbour nosiest and boring cow in town,who eyes nearly popped out ..caught red-handed smooching another
When a male hears the song "did it on em" by nicki minaj, he approaches the nearest female and grinds his gentalia all over her leg. the male also places one of his hands upon the back of his head. By doing so, he has shitted on her.
This act is best when done to over weight black women.