Are you busy tonight?
Speak as Fred
Speak as Rob
Rob: Yes, I have plans tonight. Why?
Fred: I am having some people over to my house for dinner, and I was wondering if you would like to come.
Rob: I wish I could, but I have other plans tonight.
Fred: What are you getting up to?
Rob: I have dinner plans with my old co-worker. He called me last week and asked me to get together.
Fred: That sounds nice.
Rob: Anyway, I am sorry that I can't come to your dinner tonight. Let me know the next time that you have people over for dinner, and I will definitely come.
Fred: Don't worry about not coming. I didn't give you much advance notice, but I will definitely let you know the next time.
Rob: Great. Have a good evening.