Similar to its fathering phrase "thanks for nothing", this is the ultimate way to get sympathy or what you want from someone who isn't giving it.
Can also be used to display your disgust in someones negative attitude towards your dreams or achievements. A shortened version of "Thanks for shitting on my hopes and dreams."
"You're not getting an Xbox 360 this second!"
"Gee, mom. Thanks for shitting ;_;"
"Oh, ok, lets go!"
"Guys I learned Holiday by Green Day on the bass!"
"Haha, Greenday sucks!"
"Yeah, but the song has a killer bass line!"
"No, its stupid and even a noob whos been playing bass as long as 3 weeks could play that."
"Gee guys, Thanks for Shitting ;_;"