Think of all of the violent video games that exist out there, and how incredibly popular they are. Also, think about amusement parks; don't the roller coasters and other thrill rides seem to be pretty violent, mimicking a plunge to death? Then, consider what a lot of kids do for fun-they bash mailboxes in, smash pumpkins, graffiti walls. Granted, not all teenagers do these things, but there are some that do. So, if you combine video games, amusement parks, and some of the more edgy recreation that kids do together, there are quite a few violent freetime activities, just like in Montag's society. Their society has taken it a step further though; at the amusement parks, they actuall provide real violent activities for the kids to do. For example, Clarisse mentions that they go
"break windowpanes in the Window Smasher place or wreck cars in the Car Wrecker place."
So, the "Fun Parks" actually provide windows and cars for the kids to go destroy, to release their pent-up frustrations and violence. "Fahrenheit 451" has a lot of parallels to our society, and how people spend their free time is just one of them. I hope that helps; good luck!