Jessica Simpson and Dolly Parton are using Twitter to bond -- over their big breasts. The 63-year-old singer inadvertently kicked off the conversation Monday (November 2nd) night after she tweeted, "Aahhh chiropractor . . . Hurts so good :-) You lug these around and see if your back don't hurt!"

Simpson responded to her self-proclaimed idol, writing, "Amen, sister!"

Jessica's breasts -- and her father's creepiness -- have become tabloid fodder ever since Joe Simpson told GQ in 2004, "Jessica never tries to be sexy. She just is sexy. If you put her in a T-shirt or you put her in a bustier, she's sexy in both. She's got double D's! You can't cover those suckers up!"