Dinner for sure, unless you're @AelNire. Otherwise it's acceptable, cause it's endearing and hilarious.
I think it's probably a southern thing, although I'm born and raised in Texas and I don't know a single person who says supper.
While I was growing up, my parents referred to meals as Lunch (noon) and Supper (evening). My grandparents referred to them as Dinner (noon) and Supper (evening). It was weird. I now say Lunch (noon), and Dinner/Supper (evening, interchangeable).