Difficulties with wearing a device? discussion

It’s day 3 now and I’m really enjoying it, him included. He does have the issue of his testicles slipping out (using a smaller /45mm ring), though not as often. He tried sleeping with it last night. It went fine until I woke up at an odd hour to find him looking both puzzled and impressed because his penis had completely escaped along with one testicle. He couldn’t remove the device since the other, larger ball was keeping it in place). How on earth did that occur? Any thoughts? The girth fit is just right for us; he’s a good match. Any ideas on how it happened and how to prevent it from happening again? Thanks

what device?