This is your town, big or small. You have a rep to maintain. You gotta hold your head high around your stomping grounds. If your gonna act slutty or a fool... you take it else where! Don't shit in your own front yard, people will see you. Go across town, and shit in someone else's yard :)
Friend: "Why don't you just go home with him?" You: "I don't like to shit in my own front yard, if you know what I mean."
A line from the song Milkshake by Kelis. (The song was remade by Goodnight Nurse, who made it considerably better and funnier.) Basically, the "milkshake" stands for the woman's sex appeal. When she says, "My milkshake brings all the boys to the yard," it means she attracts all the guys in the area just by appearing there.
Girl 1: My milkshake brings all the boys to the yard!
Guy 1: *to Girl 2* It's better than yours.
Girl 1: *to Girl 2* Damn right, it's better than yours. I could teach you, but I'd have to charge.