Just as an FYI - almost all the time, decals on guns is for TV promotion because marketing folks want to see the logo or name. It's just business.
When the decals become something like a Gothic crosses skulls dripping blood "Gonna Murder Duck-Deer-Turkey Faces Lips Eat Dead Meat Grawwrrrrrr!" type stupidity, that's douchery.
Meat Stick
Widow Maker
Spray & Pray
Air Traffic Controller
Critter Gitter
Fowl Intentions
Rain Maker