Most actors who play teens are actually usually in their 30's, but look much younger.<quoted text>
Here's a couple of examples from mainstream Hollywood movies which show underage actors nude.
1. "Apt Pupil", staring 15 year old Brad Renfro. In the movie, Renfro plays a high school student. There is a scene where he is taking a shower in the schools communal shower where his ass is exposed for several seconds (there are other actors in that particular scene, all of whom are extras, also showing them nude from the rear; it is unclear whether any of them are less then 18 but Renfro certainly was. According to Mr. Maltamon, this is a pornographic movie which should be banned and those adults associated with it should be arrested for child porn. It could be that a body double was used for Renfro but, if so, it was not detectable.
2. "The Little Girl who Lives Down the Lane", starring 13 year old Jodie Foster. In the movie, Foster appears nude in a scene and is shown from the side. Her right breast is plainly visible. Again, according to Mr. Maltamon, this is a porn movie and should be banned and those adults associated with it should be arrested. Again, a body double might have been used but, if so, it was undetectable.
Most actors wear rubber overskin(costumes)to make them look naked.
Fake butts can be used too.