So long and thanks for all the brownies...

One of our student receptionists brought in cookies and brownies this morning. When asked what the occasion was, she replied "Today is my last day!" with a grin.

I happily accepted a brownie and said "Congratulations!!!!"

She giggled. After thinking about what I said, I gave her a puzzled look and said "uhh... what is the appropriate response to someone leaving?"

We (including 2 others sharing in the brownies and cookies) thought about it for a few minutes. Then I finished my brownie and went back to work.

Never did figure out what's appropriate - guess it depends on the circumstances. But if you want to make idle banter while swooping down upon free brownies, instead of taking the time to find out, what is the polite thing to say?