Well, let's just jump right in. Not all sippy cups are created equal, or even similarly. Things you should know:
1. If you have a spout sippy cup, the valve on the inside has an arrow that points to the end that should go in the part your kid drinks from, otherwise it leaks.
2. If the cup claims to be "indestructible," it may mean that when your kid whips it at the front seat from the back seat of the car, it will crack your windshield. Another reason to follow the new recommendation of rear-facing until 2 years old. On the plus side, the cup does not actually break with your windshield.
3. If you have straw sippy cups, the straws are not interchangeable. Each cup/brand has a different length straw. There's the part that your kiddo sips from which is pretty obvious about which cup it goes with. Then there's the part that goes down into the cup. These come apart when you wash it, if you don't keep track of which goes with which, you end up with a straw that either doesn't get to the bottom of the cup or that gets bent because it's too long.
4. Another note about straw sippers - there's a weird pressure thing that happens sometimes that causes the liquid to come out of the straw while it's just sitting there. On a table, in the car, in the fridge, little drippy sippy cups. No idea why. Seems to happen with all brands. Any one who can explain this phenomenon, please do. Preferably with a solution as well.
5. When you find a cup under the couch half full of old juice, expect mold everywhere. There are nooks and crannies that would do Thomas' English Muffins proud. I never needed the bottle cleaner thingy until we got to sippy cups. This will also be the time that you need a thin long pipe cleaner type thing for the straws. Running through the dishwasher will not do the trick. If you find a cup under the couch half full of old milk, just throw it out, do not pass go, DO NOT open the lid.
6. Pets and sippy cups - they will chew on the spouts and straws. If it's the straws, they will eat half the straw. This blows.
7. Sippy cup replacement parts. Exist. Enjoy your search for the correct ones.
