look up any word, like fleek:
 
1.
A post-hardcore genre of music involving down and dirty riffs with sexual innuendos and emo whines. Sex-core is a spin-off of fashion-core which involves wearing pants that are so tight they cause an automatic boner. Hence, sex-core. Often, large mo-hawks are considered a staple of sex-core and they can be used to impale the anus of other sex-core fans during the brutal breakdowns.
Sex-fashion-core kid: Dude. I was listening to bleeding through and my orgasm started bleeding

Jbulls: Dude, you're so sex-core.
by Jbulls August 13, 2007
 
2.
When someone does really bad and it's freaking sexy as hell.

Originated by Jamie Kerns.
You're so sexcore right now.
by Whoson July 13, 2004