A lack of interest in ordinary socially acceptable situations involving groups of unlike-minded people which results in an inability to effectively converse with those same unlike-minded people.
The Socially Impaired have fun on a more personal level. Our enjoyment comes from groups of like-minded people conversing and interacting with eachother in familiar places. The Socially Acceptable often herd to bars and clubs for their fun with mostly strangers.
Socially Impaired Bob stayed at home with his two best friends playing video games, watching movies, drinking beer and eating pizza instead of going to the club with Socially Acceptable Mary. They both had fun, but Mary accused Bob of not knowing how to have fun because what Bob did is not the Socially Acceptable form of fun.