Adjective: When someone is covertly Bad Ass, i.e. they do not flaunt their badness obnoxiously, but rather KNOW they are bad ass and crazy without having to prove it all the time. These people look normal on the outside, but every now and then they "let loose" and unleash their inner fun, bad ass selves. They can sometimes be menacing, but only upon a closer look.
Naughty librarians, old people with guns, cute fuzzy animals with big teeth
"Yo, man my five year old lil' bro is so cute, but he's all secretly bad ass n' shit with the G-Unit tats on his back and his hot wheels' spinning dubs."