A bobble- like a BRITA filter in a bottle! Nice and big, and there are two main positives over just buying bottles at the supermarket- I don't lose it, because it's enough money that I care about it; and it doesn't get all soft and crinkly after a few refills!
I don't really make tea or coffee- I grab one when I'm buying breakfast, but that's about it.
C
I have the yellow one. It's awesome. Even if it's open, it really doesn't spill when you knock it over - which is occasionally wonderful. The only drawback is that it can be a bit noisy to drink during the quiet moments of rehearsal.