In a nutshell it said shred your boarding pass, don't just toss it away. In the bar code and the QR (?) code there's enough information (Name, phone number, frequent-flyer information) for a hacker to take control of your account....including possibly changing your PIN.

They suggest using an electronic pass, then deleting it from your phone when you're done. Or keep your paper pass until you can shred it.

We always fly on southwest...and they keep our boarding passes...