to the cashier at the grocery store ?
to the ckerk at the bank ?
to the ice cream clerk ?
to the ? ...

ill start :
to the cashier at the grocery store : (with his cool cold voice) "Hey there, im here to pay for these, now if youre nice and serve me well, i might just smile and leave, if not..."
by that, i didnt mean that he would be or sound mean or agressive all the time, i just based myself on his famous quotes "Go ahead, make my day" and "Do you feel lucky punk ?" and his cool attitude.