Chicken wing or how old?

My class went to Children recreation center yesterday, we're bounch of 16th haggin in small children out-theme park. Even though the sun so strong and hot, our 'Big' size didn't be obstacle for us to enjoy it, act silly, and fulfill our children's games where we haven't done or in our life. I able to make me skin a bit darker, yes.... Sexy, here I come....
I saw a lovely young mother (+/- 28years) carrying a cute little baby, I stand next to her and say hi, I smiled and said"...... Ci Thuei(Chicken bones)?............." her face expression changed instantly then i realized i said the wrong words, " i mean.... Ci Shuei(How old)". I was so ashamed and try not to leave to show my gentlemen side, so then i said sorry and luckily some friends came and say nice things to her. :) This problem happens a lot, especially for someone who tried to learn other language. I was so lucky she/her husband didn't slap me or yelled at me in the public.