I've long maintained that it is mostly "children" (i.e. emotionally un/underdeveloped folks) who think it's funny and/or think that they're getting away with something and/or think are making people upset.
Last thing you want to do is "stop" it. Let them waste their time. The enemy you know vs. the enemy you don't, see? If you block them they'll just find a new way to get through, and next time around it will be even harder to filter/block/stop. Let them think they're getting away with something. It's easy enough to filter or ignore.