The ability to make juice comes with The Sims 2: Seasons. Drinking juice will fill a Sim's hunger bar, but drinking juice while full does not appear to affect a Sim's fitness. Drinking juice will satisfy a PlantSim's water need. If Open for Business is installed, a Servo can drink juice and benefit from it.
Juices are made in The Main Squeezer 235X, which can be bought in buy mode for §800. It can be stocked with fruits and vegetables obtained through gardening, and once stocked, teen, adult, and elderSims can use it to make juices. If there is enough produce in the juicer, it is also possible to Serve Juice, which makes a six-serving tray. While children cannot make juices, they can drink from a tray that an older Sim has made. In practice, it appears that making a juice tray requires six times the amount of produce that a single glass requires. (This is contrary to what is stated in the Prima Guide for Seasons.) Juice made from Tasty or Mouthwatering produce will have special effects on Sims who drink it.