Frogs have very special skin! They don't just wear it, they drink and breathe through it.
Frogs don't usually swallow water as we do. Instead, they absorb most of the moisture they need through their skin. Not only that, but frogs also rely on getting extra oxygen (in addition to what they get from their lungs) from the water by absorbing it through their skin. Because frogs get oxygen through their skin when it's moist, they need to take care of their skin or they might suffocate.
Sometimes you find slimy frogs. This is because the frog skin secretes mucus that helps keep it moist. Even with the slimy skin, these frogs need to stay near water. Toads on the other hand have tougher skin that doesn't dry out as fast, so they can live farther from water than most frogs.
In addition to jumping in the water, frogs and toads can get moisture from dew, or they can burrow underground into moist soil.
Frogs shed their skin regularly to keep it healthy. Some frogs shed their skin weekly, others as often as every day! They start to twist and turn and act like they have the hiccups. They do this to stretch themselves out of their old skin!