A little etiquette, people

I just got a call from some dude asking for a reference for some other dude who at first I couldn't remember and then realized was a very annoying customer of ours. Perhaps if the annoying customer had called/emailed/smoked signalled to ask me nicely for a reference, I would not have been forced to explain to the dude that I have had about ten minutes worth of interaction with the guy, only two of which involved me not wanting to stab him in the heart with a sharpie.