I prefer "bon appétit" or "itadakimasu", because those are serious expressions used by real people in real life. One is wishing others to have a nice meal, and the other is to inform you're about to start eating.
"Rub a... whatever" sounds like a joke, that only kindergarteners would use to be funny. Certainly not something adults or middle/high school students would use. I really hate seeing it, since it's so unnatural and divorced from reality. At least use "Let's eat" or "Thanks for the food" or something like that. "Zoom zoom" isn't any better, frankly.
@LuluDaebak
You say you used "bon appétit", but I can't find it. Did you remove it at some point? If so, why?