Is it weird to have dinner with a female co worker to discuss business?

That used to be called normal human interaction before it became illegal to be social.

Its business, why would a vagina change anything

It’s not weird, don’t make it weird.

Not a thing weird about that.

Not at all weird

Nope, not weird

No.

Depends on the context really.

No. It's WORK.

Business dinners are very common, what's on your mind that you ever question this?

It depends. Is this the norm in your industry or at your work place? Have you ever had dinner with any other colleagues? Is the business dinner at the type of place where business can be discussed as opposed to a bar with loud music? It all depends. Could be perfectly normal or not. In this climate watch yourself and keep it all business.