When someone is completely wasted and are acting in an embarrassing manner and no one likes to be around them. They usually appear unattractive to everyone else except themselves and usually think they are really talented dancers. They are also prone to barfing. A fat mess is NOT a hot mess OR a tranny mess OR a hot tranny mess but they think they are.
"Michael-Ryan was a giant fat mess last night after he drank way too much before 9pm...then he thought he was a really good dancer and got kicked out of the bar cause he really wasnt"