How Do I Respond to This?

As the phone call ended she said “Have a big one.”

What does that mean?

What is she referring to? Was it a slip of the tongue or intentional. Is this the newest fad in greetings and salutations. Is it similar to cool, groovy, awesome or tubular. Does my ignorance show my age. Am I just not cool enough to get it.

Maybe it is nothing. It probably is. Whatever, it threw me for a moment.