Have you ever known someone who believed that he was better than everyone else? Someone so arrogant that it is uncomfortable to be around him? I think we can all call someone to mind.
Close your eyes and picture that person. The way she walks, holds her head, sneers when you talk. The way she turns away from you when you approach. The way her eyes scan your clothes, your body shape, the style of your hair.
Think of a coworker who knows everything, even information that is out of his area of expertise. Imagine how he reacts when you make a logical suggestion. How he fiddles with his pen when you speak. How he always sits right next to the boss and leans over in comradery when you submit an idea for discussion.
Think of the parent who shows up at every class party and outing. Picture him carrying in a box a cupcakes from a well-known bakery. Think of how the kids react when they see all that colorful icing piled up on top.
This is the person that your character meets.
How does your character handle the interaction? Does he hurriedly walk away? Slink into the background. Look down or turn away? Flush crimson? Stammer?
This is your task. Write a scene in which your character encounters a perfectly obnoxious person. Make sure that your character reacts in a way that is appropriate for her personality.
Good luck with this one.