So As A Person With Food In Your Mouth, You Have A Couple Of Responsibilities

Well, you have multiple. But let's start with these:

#1: Don't make smacking noises. This can be solved by chewing with your mouth closed and breathing through your nose. Most people are physically and cognitively capable of doing this.

#2: Under no circumstances should you speak. Ever. This can be solved by having common courtesy, manners, and a basic lack of barbarism. Most people are physically and cognitively capable of doing this. If you are, at the moment, behaviorally incapable of doing this, you can be trained.

And if you are physically and cognitively capable, but unwilling to do either of the above, you should look out because you deserve what's coming to you.