"I'm a sexy cat." Boring. "I'm a titty cat." Much better.
Sexy Vampire? NO! "I'm a trampire!" Yes.
Sexy nurse? Get specific, "I'm a sex-ray technician." Or instead of a phlebotomist, be a feelmybottomist.
Don't be a sexy cowgirl, be a WOWgirl.
Pocahontas? Nope. Pokeahotass.
Sexy robot? I think not. A hobot, a rohot, or a bimbot are the only way to go.
The sexy undead? I think you mean Aberzombie and Tits.
I can't wait for next year.