I locked the doors and left the engine running as it was a hot summer night. Then I started kissing and fingering her. I heard him tug on the door handle and looked up at him, giving him the universal "shhh" sign. I continued making out with her as he watched thru the window and windshield. I raised back so he could have a better look at her body while I continued fingering her. She opened her eyes and saw him staring thru the windshield, it startled her and she tried to cover up. I told her to just relax and continued kissing her. After a moment or two she settled in and seemed to be enjoying the situation so I asked her if she wanted me to let the window down.