In the episode of Jesse where Kurt is being very mean to Jesse, and they are discussing his 'jerkiness', Jesse orders a bowl of soup and when she takes a bite, Kurt says the guy that gave it to her had strep throat. She pushes the bowl back. About two seconds later, she re-pushes it back from it's original place.
It's doctor Danny who is having lunch with her and she says "that guy looks familiar" or something like that. The Dr. Danny says that he treated him for Strep Throat that morning. And Kurt is mean to her in every episode.