My fat finers too big for the back pocket so I go back notebook with spares, left Red, right yellow. As I'm a) right handed so blow, and right hand goes down (gives a couple of seconds for people to turn. Also, means i can blow and straight out with the red at the same time.
and for those thinking about the fat fingers and note pad - I write my info on the back of the YC. Masking tape and pen. Needs to be a worthy effort to get the pad out. Plus when you are going to write maybe a verbal warining and put a plyers number down, they don't half sh*t themselve when they see the YC ome out (but not up!)