An example of impolite is not introducing your date to a friend you see.
"Permit me to say," returned the dragonette, "that you are rather impolite to call us names, knowing that we cannot resent your insults.
You know, my mother always said it was impolite to stare.
Writing a letter asking someone for money may seem difficult, or even impolite.
Soba is served both hot and cold and it is not considered impolite to slurp while drawing the noodle into your mouth.
Choosing favors when another person is hosting the party could be considered impolite unless the host asks for input or suggestions.