Cheeks

Student:  "Mrs. A, do you ever shake your head from side to side so fast, you're cheeks move?"
(student demonstrating)
Me:  "Can't say that I have."
Student:  "You should try it."
Me:  "That is probably not going to happen."
(student still shaking head so cheeks move)
Me:  "So, why are you doing that?"
(student pausing)
Student:  "Not sure...I saw it on TV."