Wiktionary
n. (context chiefly US English) A fictional pastime wherein a person sneaks up on a sleeping cow (at nighttime) and pushes it over.
Wikipedia
Cow tipping is the purported activity of sneaking up on any unsuspecting or sleeping upright cow and pushing it over for entertainment. The practice of cow tipping is generally considered an urban legend, and stories of such feats viewed as tall tales. The implication that rural citizens seek such entertainment due to lack of other alternatives is viewed as a stereotype. The concept of cow-tipping apparently developed in the 1970s, though tales of animals that cannot rise if they fall has historical antecedents dating to the Roman Empire.
Cows routinely lie down and can easily regain their footing unless sick or injured. Scientific studies have been conducted to determine if cow-tipping is theoretically possible, with varying conclusions. All agree that cows are large animals that are difficult to surprise and will generally resist attempts to be tipped. Estimates suggest a force of between is needed, and that at least four and possibly as many as fourteen people would be required. In real-life situations where cattle have to be laid on the ground, or "cast", such as for branding, hoof care or veterinary treatment, either rope restraints are required or specialized mechanical equipment is used that confines the cow and then tips it over. On rare occasions, cattle can lie down or fall down in proximity to a ditch or hill that restricts their normal ability to rise without help. Cow-tipping has many references in popular culture and is also used as a figure of speech.
Usage examples of "cow tipping".
But it sure as hell wasn't a teen prank, like cow tipping, as the sheriff implied.
In fact, until ESPN became desperate to fill in the late-night time slots between professional lawn darts and reruns of Australian-rules football, turkey bowling was a completely clandestine sport, relegated to the dark athletic basement of mailbox baseball and cow tipping.