It used to be in older text of vietnamese history that close male friend would sleep together "leg on top of leg" - which means 2 men sleeping next to each other, and are good enough friends that they let their guard down, becoming carefree enough to not mind where he's sleeping and literally/physically put his his leg over his friend's leg (so he's taking over the bed in a sense). Could be done by both. I used to sleep with my father until I'm like 15 and I regularly put my leg over his leg - it's pretty comfortable and easier to sleep that way.

In the US that shit would probably gets me weird looks if they learned that I did that. What's perfectly normal in older time are no longer so right now, and I'm not even sure if it's for good reasons or not. Of course, needlessly having to ask, I've never considered my dad had a penis (or me, for that matter) in that circumstances anyway.

So yeah, cultural things.