Sex or Violence?

It really depends on how old the children are when they are exposed to stuff like this... and probably how intelligent they are in terms of exerting self controls and have a sense of what's realistic and what's not.

Let's say we have a 7 year-old boy, if you show him explicit images of sexual intercourse, I don't think he has enough knowledge to know exactly what the couples are engaging, the kid may have awareness that breasts and genitals are taboos, and may say "ewwww..." and walk off, but there's no driving force for him to try this out.

Violence on the other hand, could be more dangerous if the kid's exposed too much of it, again, you need to count in the fact of self control and integrity that separates reality from virtual environment. Since slapping, beating up others are much easier than taking off your pants and find a partner to have sex with, along with the additional factor of imitating coolness such as beating another kid into a bloody pulp followed by a smirk, and walking away under the sunset, a kid will tend to copy these more often.

Jam it back in, in the dark.