My three year old son is allergic to MSG. Really allergic. If he eats it, he throws up violently until it's purged from his system...just like his Daddy. We discovered this last Thanksgiving. It's not a big deal, because we rarely eat anything with MSG in it.
I have shown the kids the mega-container of MSG available for purchase at Smart and Final (a warehouse store) and mentioned that I could kill their Daddy with it.
The other day, Troubles was not feeling well and told me he felt like he had "The Terrible Salt" in his belly. How's that for reasoning from a three-year-old?