Decided to take a look at this, as I've started looking at the Java.
ItemDatabase.java has support for Ode/Milk, Glorious Lunch, Gourmand/Neurogourmet and Munchies Pills, which seems to be via creating an effect matrix, to allow one or more of them to be active at once. I guess this is to avoid having to refresh the Item Manager panel when the effects change. Adding more effects into this would significantly increase the size of that matrix, as it'd be adding extra combinations, especially as it should ideally include tuxedo shirt, salad fork, salty mouth, frosties mug, sushi doilies, grains of salt as well as field-gar.
In addition, the support that it does give to Munchies pills appears to be wrong, as it just gives +2 adv, rather than +3 if item gives 1-3 adventures, +2 if it gives 4-6 adventures, +1 if it gives 7+ adventures.
I rather suspect that a change to support this would involve changing the way this support works, if my guess as to why it calculates a matrix once rather than recalculating on any of these items being used is correct.
Well, going to wait for guidance from my betters, but here is at least a munchies pill fix :