I once sat in a parking garage with a girl while we both masturbated in my car. NO radio or anything. Just the sounds....
Every so often I would make her bring her fingers to my mouth so I could taste her (she LOOOOVED that) and I would make her taste herself as well (I LOOOOOVED that).
It was pretty intense. You need to have a good comfort level for that other wise it could get awkward at some point.