Nookser (newk ser): The part of a seat belt, harness, or other restraining device that goes in between the legs.
When we took a ride on the sky swing, there was a nookser that prevented us from slipping under the seat belt.
The part of a restraint system (seat belt, harness, etc) that goes between the legs. commonly refered to as a "croch strap".
When I went on the sky swing, the seatbelt included a nookser to keep me from sliding under it.