A rude person is ...
Une personne impolie c'est ...
an embarrassment to society
loud and obnoxious.
mean-spirited, insulting, inconsiderate, and selfish.
selfish, bossy, ignorant and narrow-minded
somebody who burps and farts in public and doesn't even say "excuse me"
someone who doesn't thank me or asks me to do something I'm not comfortable with or talks really loud at inappropriate times.
someone who doesn't think of others feelings, who says mean things for no reason, who interrupts, and who asks a question then talks to someone else
someone who is only aware of themselves. inconsiderate and loud. self absorbed.
someone who looks out for themselves while knowingly hurting others to do so.
irespectueux
quelqu'un qui ne dit pas bonjour, au revoir, ni merci.
quelqu'un qui ne prête pas attention aux autres, qui les méprisent.
Quelqu'un qui ne respecte pas les autres.
quelqu'un qui ne respecte pas les autres.
quelqu'un qui ne respecte rien ni personne.
un irrespectueux
une personne mal élevée
une personne mal élevée.
une personne sans éducation
Discussion
It seems as though a common answer for you guys was poorly raised unless I am understanding that incorrectly. I didn't think about that when I was writing out my answers but that is something that does reflect on a person as they get older.
The French answers seem to generalize rude people, while the American answers give examples of rudeness.