Tennis balls can't open locked car doors.

The life hack: If you've locked your keys in your car, squeeze a tennis ball against the lock to send a column of air into it, moving the pins and unlocking the door.

Why it's bogus: The hack was a viral stunt in 2007 that has since been disproved by a myriad of internet strangers and the Mythbusters themselves. There's just no science behind the technique.