To cease, end, or give up (doing) something in which one has found some amount of success, especially so as not to risk spoiling or reversing that success. Look, that's good enough for what we need, so let's just quit while we're ahead. If we monkey around with the settings too much, we could screw the whole thing up. As soon as I made a bit of a profit playing poker, I decided to quit while I was ahead—no sense ending the night worse off than I began. I appreciate your compliment, but you should quit while you're ahead, because you're starting to veer off into creepy territory.