I was at ASDA a little earlier, with a youngish male checkout operator, who I thought was very good, asking me if I needed a hand packing?
"No, thanks, " I replied cheerfully, "I have two good hands right here."
"It never hurts to have an extra hand!" he shot back at me.
"Rather like Zaphod Beeblebrox" I offered.
"He had three arms and two heads" I added, helpfully.
"Ah, we didn't do Greek mythology at school!"
There's just no answer to that...