Spanish for bottom

After school today Lizzie said, "Anna Claire! Do you know what Mrs. Fish (she's the Spanish teacher at Lizzie's preschool) said today? 'Sit on your hiney!'" They laughed and laughed. Then Anna Claire said, "Hiney must be bottom in Spanish!"
So I called Mrs. Fish to tell her the good news. Honestly, I am afraid Anna Claire will try to tell some of our Spanish-speaking friends the word for bottom.