This one is a little heart breaking. How long were they at Walmart to where the mom forgot that she took her kid there with her? You really have to be in the zone if you're going to forget your kid. Although there's one other possible reason. This kid might be a teenager. Teenagers are very forgettable. They are the sewer rats of society, always lurking in the shadows. As you can see, I don't have a high opinion of teenagers.
No one knows the horrific conclusion to this story where the mother didn't recognize her kid after she drove back. They go to the doctor and find out she has early stages of alzheimer's. I know that's a heartbreaking story to put on this funny image, but don't act like you weren't all thinking it.