I used to be exactly like this in high school. Whenever there was a situation that was with friends of friends who I didn't know me and one of my friends (Who I know feels the same way) would act out and joke around, get naked or do stupid stuff just to show we weren't nervous. I've gotten over it now that I've matured. Now I would say I'm more on the shy side but I can contribute to nervous situations in a constructive way without showing my embarassment. So I would say it may just be something you need a few more years and a bit more life experience to grow out of. Just be careful not to start using drink and drugs to cover your nervousness. I used to drink to settle my nerves in social situations, and it worked, but then you become reliant on it to be social. You need to learn how to be relaxed by yourself in your head, rather than looking for outside help. Good luck, and remember there's nothing wrong with being outspoken if that is who you find yourself to be