I definitely get overexcited sometimes. For instance, I simply cannot contain my excitement when there's a new Doctor Who episode coming up. I'll be bouncing around with a huge grin on my face. And throughout the week when something reminds me of it I get a rush of joy and shake my hands like Wallace from Wallace & Gromit.
Another time is whenever I buy stuff online. The excitement builds as I wait for it to arrive and I tend to squeal with excitement when I check the mail and there's a package sitting there with my name on it. I startled my mail lady once when she was walking by and I squealed a little too loudly
When I was planning my trip to Vancouver, I didn't let myself get too excited because it was a spur of the moment decision of my mom's and she doesn't always go through with things. And then on the day of our flight she was late getting home so there was a real possibility we'd miss our flight. Once actually seated on the airplane I finally let myself believe that I was actually headed across the country and I was freaking out with excitement and I absolutely could not stop talking (I talk a lot when I'm excited).
This sounds like me. I get excited over new episodes of shows although I've tryed to lessen that since my parents hate me going on and on about a new HOUSE episode OMG that episode was amazing (SH! you are being to loud!) I get loud when I'm excited/vocal.