I really hate it when someone approaches us in a shop or restaurant with a cheery “Hi Guys”.  If  I were on my own they wouldn’t say “Hi Guy”.  More often than not I’m with my wife, and the last time I checked her gender was female – so she’s not a “Guy” either.  What the heck is wrong with Hello, or Good Morning / Afternoon?  I’m not looking for obsequiousness, I’m uncomfortable with Sir and Madam, but nor do I want bland trans-national ubiquity.   It’s not as if they actually want to form a relationship with me, they just want to get my order (which often is not delivered because they haven’t actually made that connection and been listening)!   Straightforward, standard English polite would do very nicely.  Have a nice day.