On one of my rides during a holiday in Auz I refueled in Melbourne. When I went to pay, I saw someone carrying a helmet in the reflection in the glass doors. As there were no other bikes in the servo, I turned around to see a young guy put my helmet in the back seat of his car. I
confronted them (two young guys) & got it back.
I took their registration details and threatened to report them to the police. I’m not 100% sure it wasn’t a prank, they were quite immature young men – but I was angry at the time.
bottom line: don’t leave your helmet unattended, even for a minute.