mariahcareyparty072311_4.jpgRafael Fondeur

New mom Mariah Carey left twin babies Monroe and Moroccan at home (and hubby Nick Cannon) and hit up Juliet Supper Club Thursday night to party with apl.de.ap and some other pals.

The super singer really let loose -- a source tells us Carey ordered a bottle of Perrier Jouet to the bathroom, as her security guards kept watch outside the door!

The source tells X17online.com exclusively, "Mariah was extremely friendly and courteous with everyone. She posed for hundreds of pictures with everyone and she danced and had a good time."

Mariah arrived around 11:30 pm and stayed until 2:30 am, shutting down the club.

Way to go, Mimi! We love a mom who knows how to have a good time!