I'm sure the guy was rude, annoying and a typical guitar shop show off, but maybe instead of indulging in passive aggressive violence fantasies, and glaring at the guy, maybe you could have tried to be assertive and simply said "excuse me..." and asked him if you could have a turn too? After all people that play heavy music, do like to crank it up a little bit sometimes to hear what those amp dinguses actually do. I'm personally never interested in what a tube amp does on 1. Doesn't your guitar center have a loud room? I'm not sure how this is supposed to teach anybody about manners, other than how you were offended, didn't say anything to the guy and didn't get to try out your guitar, and didn't get to get your friend's manager's discount.