-a name to call people that piss you off.
-an insult.

could mean...
-whore
-bitch
-dumbass
-ugly person
-pretty much anything else that is an insult.
Example 1:
Girl 1: Jessie kissed Jeff at that party on Saturday.
Girl 2: Isn't Jeff still going out with Beckie.
Girl 1: Exactly.
Girl 2: Whatta shmoon.

Example 2:
Girl: She stole my boyfriend! Damn skanky shmoon!!

Example 3:
You're a shmoon if you didn't know what shmoon meant.

Example 4:
Guy 1: Dude, did you hear Rick is dating Julia.
Guy 2: Ew! That's disgusting!!
Guy 1: Yeah, I know man. She's such a shmoon.

Example 5:
Man, I hate that shmoon.
by kimmmmmmmy1019833 December 9, 2009
Get the shmoon mug.