At this age, your kid may not be rude all the time, but need to teach your child manners, so that the habit remains for the long run. This is the right age to inculcate manners in him.
What you need to know:
Good manners seem to be a lost art that may be because manners don’t just happen, they have to be taught, just like learning to walk or talk. They aren’t just about how to use a knife and fork. They are about how you treat others, the tools you use to interact in a civilized manner. And it’s never too early to teach your kid the basics. You can take your child on a shopping trip and teach him boundaries, that he can’t just grab things off the shelves etc.