Many resources designed to help people use body language to succeed in business or romance would be appropriate to use in sessions with our teen or adult clients with social cognitive deficits. Check out this video from body language expert Carol Kinsey Goman on BNET. The video has specific examples of gestures people make with their feet that provide clues about whether they want to talk to you or not.
For example, this woman doesn't, because although she looks attentive, her feet are pointing away. She's totally over whatever the heck you are saying, and wants to go back into her fancy sliding glass door office. Where you aren't.
Crud. I probably do that with my feet all the time!
This video provides a nice jumping off point to some practice sessions with a pragmatic group!