Anyone else embarrassed to take pictures/tips?

I know, this might sound just too silly, but I'm kind of really scared to take pictures in public.
Outside in town or some nice scenery I get embarrassed when someone sees me, but it's even worse with taking pictures of people.
Tomorrow, there's my little nieces birthday and the last day of school this year, I'd LOVE to bring my camera to both events (going to my sisters right after school), but I know I probably wouldn't bring myself to take a picture.
At school we're having some christmas party, I probably wouldn't get myself to ask people if I could take pictures of them, well in class, maybe, if they would ask me, but at my sisters, no chance.
I have a Nikon D90, so it's also so loud (I know it's not, but you notice it).

Any good advice?

Just take them, its not necessary to be afraid

Skip the school. Talk to your sister, ask if she's ok with it and promise to share the best with her.

Only way to deal with this is to practice.

Sell your camera
if you are not going to use it
only you can make yourself use it

Just take that shot.

May be you can start with friends and relatives. Or best the kids. Invite them to stay in a group for you to take a shot. Don't forget to send them copies.