What do you do if someone gets in the express lane at the supermarket with more than 10 products?

This happened to me once again when I was in an bit of hurry during my lunch break. Some old hag (probably with dementia or maybe semi illeterate) got in front of me. Needless to say I was muttering under my breath but I was wondering how can I politely tell the next culprit to get the HELL OUT OF THIS LANE (p.s. the cashiers NEVER say anything)