I showed him the way I do it, something I learn a few years back from one of Chiara's workbooks and that is using your knuckles. Don't worry I didn't punch the barista in the the face!
Check this out if you want to know how to do it click here.
I love this method as I don't even use my knuckles anymore - so easy!
While we're on the subject of months here's a little fact for you: Julius Caesar invented the leap year in 45 BC