Last Thursday, a customer at the hardware store I work at asked me to help him find a 'left-handed' hammer.
I spent a good ten minutes explaining that hammers aren't handed, only for him to pull out his phone, show me a picture of a standard claw hammer, and say, 'See, the claw is on the left side, so it's for lefties.'
Actually, metric adjustable wrenches are a real tool. They have jaws that adjust to metric sizes like 10mm or 13mm, instead of inch fractions. They're not common in the US, but you can find them.
Wait, did you check if he wanted a left-handed tape measure too? I once spent way too long looking for metric adjustable wrenches before I realized the guy was messing with me.