Let's face it: Kids love stickers. They will stick them anywhere they can, especially on themselves. This can be a problem because taking off an extremely adhesive sticker can be painful and traumatic for a child. Luckily, stickers can be removed with less pain and suffering involved.
Use oil. Putting some WD 40, which is oil that comes in an aerosol can, on the skin should allow the sticker to come off the skin more easily. The slickness of the oil works into the sticker to help dilute the adhesion of the sticker. Once the sticker has come off of the skin, wash the area with soap and warm water. Even after washing, the skin may feel slick for awhile afterward.
Apply rubbing alcohol, also called isopropyl. Apply some rubbing alcohol onto a dry wash cloth and begin to rub the sticker area. The rubbing alcohol will dampen the area, so the sticker should fall off, and the alcohol should remove most of the adhesive from the skin as well. When you are done, wipe the area dry with a cloth. Rubbing alcohol may not be as slick as oil, but it cleans up a lot more easily.
Apply vegetable oil. Pour some of the oil onto the sticker, then rub it into the sticker until the sticker starts to peel off. When the sticker is off, wash the area with soap and warm water to get rid of the slick residue. Vegetable oil is convenient because it's a household item and does not have an overbearing smell (like the rubbing alcohol).
If you do not have rubbing alcohol, vegetable oil or other oils, they can be purchased at most grocery stores.