1
general::
Act as a host or hostess, performing introductions and otherwise attending to guests. For example, At home Mary leaves it to Bill to do the honors when they have guests. This expression uses honors in the sense of "courtesy." [Mid-1600s]
American Heritage Idioms
2
general::
Phrase(s): do the honors
to act as host or hostess and serve one’s guests by pouring drinks, slicing meat, making (drinking) toasts, etc. • All the guests were seated, and a huge juicy turkey sat on the table. Jane turned to her husband and said, "Bob, will you do the honors?" Bob smiled and began slicing thick slices of meat from the turkey. • The mayor stood up and addressed the people who were still eating their salads. "I’m delighted to do the honors this evening and propose a toast to your friend and mine, Bill Jones. Bill, good luck and best wishes in your new job in Washington."
McGrawhill's American Idioms And Phrasal Verbs