"Stop being childish" or any of the variations of telling a person to 'grow up'.
Ya know what? No!
Not only is the idea that age is comparable with mental maturity completely bullshit, but it's also used so often by jackasses who like to leverage the real life version of "stop having fun guys".
If I wanna act like an idiot in my spare time and enjoy DnD and other assorted fantasy (not saying that DnD is acting like an idiot, that's kinda my point), then it's my fucking right to do so as a decently-fuctioning member of society, and you have no business judging me because of it by such a retarded standard.
And just because you let your inner child die to fit in with what society considers 'normal', don't go around trying to kill mine too.
And going with that tangent "It's not normal".
Normal is completely subjective to the person who sets the standard, and even if there was such an actual thing as 'normal', what makes it so important that everyone confirms to that norm? What is so horribly offensive about the fact that someone has different interests than most people, or enjoys different music, or dresses differently, that it completely justifies systematically breaking them down mentally and possibly fucking them up for life? If I wanna have long hair as a guy and listen to metal, I have the fucking right to do so without problem! If I'm overweight, then I suppose I've decided not to actively get rid of that problem, and you should shut the fuck up over it. If I happen to have read hair, then that's hardly my fault, so leave that alone, just like the fact that I need glasses, and HOW MANY FUCKERS DO I NEED TO RAM HALFWAY THROUGH A LOCKER TO MAKE THIS FUCKING CLEAR?!?!
......I may have gone to a bad place there for a sec. I'm gonna go....read a book or something.