1. See "sexy" in a real dictionary.
2. "Sexy" for idiots that can't spell, or think that corrupting the English language makes them "mod" or "hip" or "alternative" or "crunk" or "swell" or "bitchin" or whatever the hell the kids are saying these days. This concept is also evidenced by the gradual substitution of "z" for "s" in plural noun forms.
"Words" like seksi corrupt the English language and make our children dumber by the generation because people are forgetting how to write properly.
When one's nipples and breast tissue is hypersensitive to tactile manipulation by another person—most likely due to extra nerve endings in these areas—thereby creating a heightened sense of pleasure and arousal.
1)
Darnell: "Yo, I was smashin this chick out last night right, but all the bitch wanted me to do was suck on her titties!"
Bartholomew: "She musta had mad Sensititity, son."
2)
Matt: "Why the fuck does your girl have metal plating on all her bras man??"
Kyler: "Cuz dude, she's got a severe case of Sensititity and if something touches her nips she'll have an uncontrollable orgasm right there in public.
One's own ability to react/respond to the artistic style of another.
The artist told me "I respect Tarentino's work and talent, but it's not my sensibility." (actual conversation quote from New York artist Chivas Clem of Maccarone Gallery.)