No matter what holy text you prescribe to, bragging about charity is usually a big no-no. I'm pretty sure Satanism even has a clause against it. I mean, no one needs you to tweet every time you give a homeless person a dollar outside of 7-11. It's just not that big a deal. Take it to the next level and that's when you start lying about charity.
A restaurant goer wanted the world to know that he gave a generous tip around Christmas time. Strike one, he's bragging about it. Strike two, as one of his Facebook friends points out, he's showing the customer copy, which means he most likely never left that tip on the real receipt. I appreciate the extra bit of realism with the cute little "pay it forward" note and all, but come on. Just don't lie about this stuff.