Sisturd, don't be peeved because I called you out for not contributing your fair share for Mom and Dad's birthday gifts. It's not my fault you smoke all your money.
Sistard sĭs'tärd' - noun - female offspring having both parents in common with another offspring; also a female sibling; that is also slow, dimwitted, and/or appears mentally challenged with the severe level of intelligence deficiency, yet is allegedly cognitively normal according to the standards set by society.
The act of dating a girl then to date her sister, known as the sister swap, if you swap back to the first sister, that is called the swap back. Though the definition of Sisterdistic would be equal to the swap back and back again.
Dave has beendating the Smith sisters on and off for quite some time now, they must be Sisterdistic.