This one can sound like a mess but works surprisingly well in practice. The man begins by sitting with his legs spread apart but not so far that the woman cannot sit in his lap. The woman sits in his lap while his legs are still in a sitting position. She raises her legs to around where his elbows naturally rest and then wraps her legs around his back. The man then needs to support hers legs, back and neck. To get the most from this position the man will need to rock back and forth rather than thrust.
The Double Elbow