Oh, they say things like that at my work too. I work in customer service. I never thought of myself as crazy. Are you sure they think that about you? We dont say nutters, maybe because we' re in the states. I never thought about it , but can be a hurtful term to be calling people. I' ve used the term to describe customers when what i actually meant was kooky, unreasonable, silly, or exasperating.