That was exactly my thought as I was reading the OP. Pissing off the waitstaff at restaurants is not only rude, but incredibly stupid. As is, there is already

That was exactly my thought as I was reading the OP. Pissing off the waitstaff at restaurants is not only rude, but incredibly stupid. As is, there is already a chance that they don't like you for some reason and spit in your food regardless of how nice you are.