boo-boo face
n.— «You’ll stomp your feet and put on your best boo-boo face and spew forth about how you’re not coming back, and that this time you really mean it. But you’ll come back. You always have.» —“Mother Of All Strikes Premature End To Season Could Help Baseball In Long Run” by Stan Savran Pittsburgh Post-Gazette (Penn.) June 11, 1994. (source: Double-Tongued Dictionary)