9. She'll keep you from trying on/going near any suits that could possibly embarrass HER if she's seen with you.
8. She knows whether tank-ini's are in or out this season.
7. You can be the first to explain to her WHY they put that sticky thing in the crotch of the suit, and WHY you don't dare remove it.
6. You'll also be the first to explain to her why/when/how there comes a time when serious padding and underwires are not optional.
5. She'll laugh hysterically at you when you can't get the size 10 bathing suit past your knees.
4. You'll both almost pee in your pants when you explain to her that you thought it said size 10...it was really a size 01!
3. She'll tell you honestly which parts of your body to cover up and which are still appropriate for public viewing.
2. She'll tell you with a straight face that you should "seriously get that suit" because it matches the color of your varicose veins.
And the number one reason why you should shop for a bathing suit with your 10 year old daughter...
1. On the way home from the mall, you can both sing "Don't Stop Believin'... " as loud as you can, just like you used to do with your college friends.