It is polite to greet someone happily.
Rod stops at the same bodega every morning on his way to work for a bagel.
Rod wants to greet the bodega worker.
"Rod enthusiastically says ""good morning"" with a big smile as he pays for his bagel."
Rod nods at the worker without saying a word and leaves with his bagel.
The bodega worker thinks Rod is a nice man and gives him a free bagel once in while.
The bodega worker thinks Rod is a very rude person and gives him slow service.