system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do sex scenes in movies work?
gpt
They don't really stick it in if thats what you want to know. Its a lot like wrestling, they don't really punch. They kiss and grope but they usually cover up the female genitals, there are lots of way to do that, stringless panties for example. 
Body doubles are sometimes used if an actor or actress is not hot enough or if they are not willing to or have too many tats and so on.  
Usually on a set, there are lots of people standing around, so its not as romantic and hot as it may seem in the actual movie.