Abstract: A gable top carton for containing a beverage or like liquid product is diosed which comprises a boxlike body having a closed bottom and a double sloping top. The top has an aperture defined in one of its sloping sides for pouring out the contained liquid. Closing this aperture is a plastic mouthpiece of one piece construction, which is fused to otherwise watertightly attached to the edge portion of the top around the aperture. The mouthpiece includes a lid having a pull tab protruding therefrom. The lid can be torn open upon exertion of a pull on the pull tab. Preferably, the pull tab is formed integral with a hook capable of engaging the ridge of the gable top when the lid is torn open, so that the lid may be held fully open as the liquid is poured out.