Unwanted Reaction To The Joke

(I’m at a popular burger chain with my boyfriend. Due to allergies, I can’t have mayo. I order some food, and when I order my burger…)

Me: “And no mayo on the [burger], please.”

Cook: *pops out of the kitchen* “Extra mayo, then!”

(I know he’s joking, but I give him the most dead serious look.)

Me: “I will vomit on every surface I can if you give me mayo.”

Cook: “…No mayo it is.”