While BBQ; my girlfriend and I saw (flying North East) in the sky, what I thought at first to be an extremely fast object, thinking it was a plane, I continued to focus. Then I realized it was flying faster than a plane, but the shape was like a stretched square or diamond shape. As I continued to look at it speeding by, it appeared as it had heard me and it stopped in mid air, and started gliding for a few seconds seconds; then it it sped up and vanished Northbound.