Doonesbury by Garry Trudeau for February 16, 1976
Transcript:
Man: P'ing! What are you doing here?! you're supposed to have driven Ambassador Duke over to the welcoming banquet! P'ing: He hasn't come down yet, sir. Man: Hasn't come down yet?! The banquet started an hour ago! P'ing: Yes, sir. We think he might have forgotten. His translator just went up to get him. Honey: You're off to a bad start, Mr. Ambassador. Duke: How's that, Honey?
I think it was just an affectation that morphd into her nick name over time.