Ugh. I think my reply would be something like "I'll trade you, Why did you come to a party?" Or "Why do you ask a question like that at parties?" or maybe just

Ugh. I think my reply would be something like "I'll trade you, Why did you come to a party?" Or "Why do you ask a question like that at parties?" or maybe just "Why do you ask?". Somehow bounce that right back on them. Force them to declare their own odious transparent self-important nature, or wriggle on the hook trying not to.