Goodbye isn’t good enough. When people are compelled to add an additional “You have a nice one” upon parting, smile brightly and reply “thank you!”

FAREWELL! thou art too dear for my possessing
And like enough thou know’st thy estimate:
The charter of thy worth gives thee releasing;
My bonds in thee are all determinate.

Sonnet LXXXVII by William Shakespeare, Farewell! thou art too dear for my possessing