The rock 'n roll head banging motion made by a baby/small child while trying to fall asleep in a seated position. The baby/small child's head slowly nods down only to be jerked back up from the uncomfortable position, creating the head banging motion.
Lancashire (where we talk proper): Baby's head. Noun, Steak (and sometimes kidney) pudding, especially when ordering from a chippy, and so called because of it's close resemblance to a baby's head. Most commonly ordered with Peas and gravy.