"Do you ever think about me sucking your cock, professor?"
You can't help think about it, and remember how amazingly arousing her cock-sucking is!
But you shake your head, trying to shake yourself out of the teasing fantasy she is re-creating for you.
"No? But I'm *really* good at it! I just love feeling a thick, juicy cock twitching and throbbing while my tongue teases it all over and wraps around it, teasing the sperm out!"