You can do better. It started one night when we realized that we were both pining over the respective guys that we were seeing (or maybe more accurately, trying to see) and evaluating our own behavior towards them, asking what we could have, should have, would have done differently.
Then we realized that we could have, should have, would have done nothing. If the way these men were treating us was making us unhappy, then why should we be questioning ourselves? And "You can do better" was born.
We realized that if someone's behavior is a source of unhappiness or discontent, then not only would we be unable to change the person to make us happier, but it wouldn't even be worth the effort! So we made a list of everything that made us unhappy, everything that we should not allow ourselves to settle for, and said that if someone we were seeing belonged on the list, then we could do better. Sometimes it's funny, sometimes it's heartbreaking, but it's always true. And once it was written down, it was like a big dose of reality and empowerment rolled into one.
The purpose of "You can do better" is not to set impossible standards or refuse to compromise. "You can do better" is about not compromising respect and fulfillment. It doesn't matter if he's into you or not, but if he can't pull it together for you, then you can do better!
If you're in a relationship and he refers to you in conversation with exes and/or female friends as "some girlfriend" (as in "I was at the party with some girlfriend"), then you can do better!
If you've confessed to having liked him for more than a year and he drunk dials you one night to ask if he "should go to bed or...", then you can do better!
If he invites you to his concert, where you don't know many people, only to ignore you most of the night, then you can do better!
If he says he likes you, then starts hooking up with your best friend, but tells you he still likes you a few months later, then you can do better!
If he gets you a stuffed STD bacteria for your birthday, then you can do better!
If he spends the whole night telling you how awesome he is while trying to look down your shirt, then you can do better!
If he asks whether a friend of yours is seeing someone, and on learning that she is, asks whether you are and says you're "pretty cute," then you can do better!
If he is a shameless flirt with you and every other girl in sight, but he turns out to have a girlfriend, then you can do better!
If he hits on you all day and then invites you along as a third wheel on his date, then you can do better!