A Sneetch refers to the Dr. Suess story of the star-bellied sneetches. It means someone who is stuck up and think they're better than others due to things such as the way one dresses or other unimportant aspects. It does not refer to a woman's vagina, that would be a SNATCH.
Man, that guy is a total sneetch.
Gee, for what they are, crustpunks are real sneetches.
Watch out! The beaches are crawling with sneetches!