Advice please!

Thanks to her older brothers, my 2 year old is saying "You're a poop" to me, Daddy, Brock etc. She is using it in the right context and with conviction. What do I do? If I put her in timeout, she fixates on it and continues to use it. If I ignore it, Brock constantly tells me she is saying it to me and he knows it's not right. Help! Anyone know the right thing to do? Or at least to make it stop?