A hand gesture used during an awkward moment. 'Ox' as in 'awks', the short form of awkward. This gesture is used to express that the situation is awkward. Depending on the situation, it can either make the situation more awkward or help clear the air. The mad ox is created by holding your index fingers up at the side of your head like ox horns and making an angry face.
Boy: Just call me milk, I'll do your body good
Girl: Oh...um... that's cool