I’d say sex in cars, but that’s lame – who hasn’t done that?
Here’s one: I drove a motorcycle without a license or helmet for about a year.
My friend and I had an elaborate plan to evade police. It involved back roads and shortcuts (I’d be able to navigate the streets on a bike far better than they could in a car), ditching the motorcycle in someone’s yard, and making a run for it. Once police ran the plates, they’d contact my friend who’d say the bike should be parked outside—and if not, it must have been stolen.
My girlfriend (now wife) was not impressed.