Having a date/mate that is significantly more attractive than you.

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

When a guy has a girlfriend who is way out of his league.

Dating or marrying a woman that you can't possibly satisfy, thereby assuring she will be back on the market in a short period of time.