That's something I teach in my concealed-carry classes. Never post anything online that you wouldn't want introduced as evidence someday. (Sadly, I've been told to "f*ck off, I post what I want" more than once.)
I also teach "if you wouldn't go there without a firearm you probably shouldn't go there with one", on the premise of "don't start sh*t, won't be sh*t". The response from those same people? "F*ck that, I go where I want and my gun makes sure I can!"
Luckily, they're quite rare.