Take it Down a Notch

instruction to an individual to regulate his or her level of enthusiasm.

Robert needs to take it down a notch with the flirting; he already has a girlfriend.

take him down a notch

If somebody is taking more than his fair share, or thinks he's all that, it's time "take him down a notch." Put him in his place.

To take someone down a notch, you don't have to insult him. You just beat him at his own game.

I took Mister Hotpants down a notch. His so-called girlfriend gave me her digits.