If your only nice to the people that are nice to you, big deal; what do you want, a gist certificate? Everyone does that. And if you only say "hi" in the hall to the people that say hi to you, what are doing more than anyone else? Maybe you know people who are different when they're alone than when they're with their friends. they might say "hi" to you if your alone, but with a group they act like they've never seen you.