Could i have handled this question better?

my 2 and a half year old is my little helper when it come to her little brother and she prides herself on it. anytime i am changing his diaper she will bring me a diaper and a wipe and rub his head to keep him calm. the other day she asked me why his 'toot" stuck out, and if it was a boo boo and if he needed it kissed :X of course i told her "no it wasnt a boo boo and he was fine" but she kept asking me why his toot stuck out, so being that my daughter is very smart i just told her the truth, i tol dher that girls have toots and boys have peens, she got it, i was very relieved it didnt go any further till later she was walking around the house saying that mommy has a big toot and daddy has a big peen, omg, i know she is just refering to us being bigger than her and her brother, but she has been saying it a few times for the past few days, how can i get her to stop or what should i have told her so it didnt go in this direction...