Use A Handbrake
There’s a reason they build cars with handbrakes. Even though most people don’t use the handbrake when they park their car, there are times when you need to. This photo is reason enough to use a handbrake, even if you’re not parked on a slope. Someone who parked on a ferry forgot to put their handbrake on, and the result is detrimental. Their car slid off the ferry and into the ocean. Unfortunately, there’s no way they can get their car back, and if they manage to, it’s just ruined (via Reddit).