Usually just water from a little bottle that hangs on the cage. You can get them at any pet store.
What do hamsters drink?
The best thing for you to give a hamster to drink is just plain water. This is what they need for their diet. Like most creatures, they need water to survive, so make sure that if you have a pet hamster, they have constant access to fresh water.
The best way to give your hamster water, is out of a bottle that you attach to the outside of a cage. A thin metal tube goes through the bars of the cage so it is easy for the hamster to get to the water. These bottles can be bought from most pet shops.
The water can also be given to the hamster in a small bowl in the cage, however it is easier for them to drink from the hanging bottles, as well as being less messy!
A hamster can also drink milk, but I wouldn't advise giving it to them all the time. The problem with giving your hamster milk is that you have to put it in a dish, as it will go off quickly if you put it in a bottle. Always keep an eye out and make sure the milk is still fresh too.
You don't want your hamster getting ill from drinking old milk.
They like water but I'm sure they would drink pop if you gave it to them.