"Why is my butt in your face?"

Eric heard Ayden in his room saying, "Why is my butt in your face? Why is my butt in your face? Why is my butt in your face?" Eric thought Ayden and Anna were in there up to something so he went and looked. Ayden was in his room by himself playing with his monster trucks and had lined them up end-to-end with their "butts" in each other's "faces".