When you really don't feel like eating but are guilted into eating. Eating, in order to "fit in".
"Oh, you better at least have a "polite bite" of your Birthday Cake!". Second example; When your Mom or someone offers you something to eat and you've recently eaten and just couldn't eat another bite. "Oh, honey just have a "polite bite", I made it just for you!". When someone insists you taste something and it doesn't look appealing to you. So in order to not offend them, you take a "polite bite".
a tone that someone has to their voice where they say the nicest thing and have venom in their voice so it doesn't come out sounding nice
"We will go to the park, won't we?"
and sounds like " We are going to the freakin park and your going to freakin love it, so shut the heck up."
and the person it was said to mumbles "easy with the polite bite"