If you are going to wear those three-piece suits to class, please buy some appropriate socks. Wait... why are you wearing those three-piece suits to class?!?!
You are cute, and I appreciate your returned smiles. But the way you look at me is getting steadily creepier. You are too old for me. Keep smiling... but lose the creepiness.
Please do not use "How are you" or "What's up" or any variation of courtesy questions in place of "Hi." These questions elicit responses, and when I am quickly walking past you, I do not have time to answer or kindly ask you the same. "Hi" is appropriate in this situation.