Beyond skinny-fat, this person is scared skinny, so as not to endure the pain of being labeled fat, lazy or repulsive, this person has went to extremes to reach an unattractively low weight that is neither healthy, sustainable or sexy in any way.
Example 1
DUDE #1: Did you see the chick that just walked by, she was hot!
DUDE #2: Are you kidding? She looked scared skinny.
DUDE #1: Oh that's right, you like your women bootylicious.
DUDE #2: And you like your women anorexic. Be a real man bro and learn how to handle a real woman!
Example 2
Award-winning playwright and author Mary Dimino claims to have been "Scared Skinny" in her New York International Fringe solo show and best selling book.
A cop car that was once a cop car, but after a police auction or something, it is now in the hands of just some random person. (It may or may not have all the accessories a normal cop car has). When driving down the road in a neighborhood, it may scare the crap out of some people who are on the road into slowing their vehicles down so they don't get busted. It may even disperse a potential drug deal in progress.
Tom: A'ight, man, hit me up wit' some udda good stuff.
Alec: Aww, shit! Hold up hold up.. Looks like we got some 5-0.
Tom: Man, that ain't the popos.. It's a damn scare-mobile!
Alec: Damn, that was close. Damn scare-mobiles got me all shook up an' shit.