By Meghan Overdeep

The restaurant industry is full of honest, trustworthy individuals. But, just like anywhere else, that doesn't mean it's immune from people with bad intentions.

That's why the next time you eat out, you should reconsider leaving the "customer copy" of the receipt when you go.

On a recent Reddit thread, one former restaurant worker explained that you never know when a blank customer copy might be seen as an invitation for staff to adjust your tip after you leave. And keeping your copy of the receipt will make it much easier to refute any suspicious charges should they pop up down the road.

Another user revealed that she goes one step further to prevent staff from tampering with her bill.

"I had a dishonest friend who I learned would change every tip that wasn't 20% to at least that. Every single one. Never got caught," onekate revealed—even though we all know it's polite to always tip 20%, right? "Because of him, I write the total amount of my bill including tip below the numeric total and above the signature line like one would write it on a check. Every time."

Sounds like a good idea to us! Like mama always says, you can never be too careful, can you?