I'm nearly fifteen and I'm seeing Avenue Q in the summer (on my birthday, in fact) with my family. If you plan on seeing it with a parent or something, just let them know what to expect. My dad's been listening to the OBCR a lot lately (he loves it!) and my mom understands its content, so that way, they aren't surprised when they see it. Maybe let your parents listen to it so that they know what to expect.
"A little rebellion, now and then, is a good thing." - Thomas Jefferson