It's surprising to see you wear a suit other than that tacky brown one you've had for over century.

 Don't be ridiculous. Just because I don't happen to waste my money on a new outfit every day like you do, doesn't mean my clothes are that old. Besides, it's a formal affair. I'm not going to wear my suit from work.

You usually come in some other tacky outfit to everyone else's parties.

I already told you, it's a formal affair. Everyone is wearing a suit so-

Not everyone.