a person who thinks he is funny but is not

A girl who, initially and on the surface, seems plain and ugly but as you get to know her is actually an interesting and good-looking one!

When your rutty duck or ruddy duck has dried up and forms a hard shell of poop around your dick/balls.

Beautiful people who didn't get pretty until high school or later, and were nice because they were ugly. The niceness carries over through life.

(A.) When a person used to be a really ugly kid, but then later turned out to be really good-looking.

A situation in which a girl who used to be ugly before puberty becomes hot, but still, in her own mind, she thinks she is ugly.
Often referred to as U.D.S.

When a person who used to be somewhat awkward and not attractive, though not necessarily unattractive, becomes extremely beautiful. Because this person used to be unattractive, bitter and jealous people assume they are emotionally damaged and scarred. Hence, they believe the aforementioned beauty is mentally demented, while they themselves are sympathetically retarded.

Ugly Duckling Syndrome is an excuse to undermine the physical and inner attractiveness of a blossomed beauty.