When a guy and a girl have sex with a blanket sheet with a hole between them in order to avoid physical body contact.
Al:"River was so shy last night that she took a pink blanket and cut a hole in it. Then we had blanket sex".
Pinky:"That's weird. She usually likes hot and steamy sex. Have you waxed your chest?".
Al:"No, why?".
Pinky:"Now I see the reason why! River does not like the Amazon forest!".
When a girl or guy takes a blanket and sticks it in between their legs and acts like their having sex with the blanket, and thrust until they get "the magic". Orgasm noises can be included if the person wishes. It's a form of masturbation.