[fuzz4lyfe]

Pretending to be naive can be useful from time to time.

"I'm sorry, I have dietary restrictions that prevents me from enjoying the free lunch. It would be a great bonus if I was able. How about this you forgo the large cost of the free lunch and instead pay me the minor amount of overtime for the rare times I'm called out." (they always present that you will rarely be required to fix something off hours, call that bluff)

The only directions they can go is "Well that will cost more than the free lunch" or "we demand it" so either you win the argument by having them make your point for you or you will have a nice casus belli to find a new job.