The urban legend of cow tipping relies upon the presumption that cattle are slow-moving, dim-witted, and weak-legged, thus easily pushed over without much force. Some versions suggest that because cows sleep standing up, it is possible to approach them and push them over without the animals reacting. However, cows only sleep lightly while standing up, and they are easily awakened. They lie down to sleep deeply. Furthermore, numerous sources have questioned the practice's feasibility, since most cows weigh over half a ton and easily resist any lesser force.