It's a type of cuddling that has become increasingly popular recently. in which one person wraps them selves to an unsuspecting person and cling to them. they have to be horizontal and if done right the person will arch their back and look like a banana and you'll look like a monkey.
It's also a pretty kinky pose and can result after they used to it, or slap you, some lovin'
We thought they were making love, but they were just banana cuddling.