The critical point is that this garbage is absorbed by overexposure to the decadent culture.
The orthodox try to shelter their children from this shmutz with the hope that they will retain a little purity and holiness.
What can the modox hope for if they lechatchila expose their children to shmutz in their living rooms?
Not true, most normal people Jewish or not, Orthodox or not, moderate what their kids are allowed to watch. It's called parenting.
You all make it sound like this kid is some yeshiva bochur from lakewood. He's not! He most probably goes to a co-ed school, has a girlfriend, and kids tell each other dirty jokes in class. Don't make such a big deal over a few silly jokes. (as if when we were kids there were no kids telling dirty jokes, please!)