Role Reversals - FUNNY idea!

I have read many posters talk about how the "Diet Nazi's" come out and either A) pressure you into eating something not on your prescribed food choices, or Razz you about something you are eating that IS on your prescribed food choices. I have wondered to myself what would happen if you pulled a "Role Reversal" on them....not that I'm yet brave enough to try it.

Scenario A
A larger coworker is sitting at his desk eating a ginormous cheeseburger, greasy fries and a half bucket of coke. You walk up to him and offer him a delicious sliced apple with peanut butter and point out to him that this ONE apple isn't going to derail his unhealthy diet choices...it's just an apple. Surely you're not cutting out ALL fruits?

Scenario B
One of your larger female coworkers is eating a cupcake. You walk up to her and ask her why she's eating THAT...I mean, she's probably just going to start eating vegetables again anyway....

Thoughts? (Or funny scenarios).