Another Cow joke I attribute to my 'Ol chemestry prof was the placement of a cow onto the roof. I would presume a fairly storng roof, but once up there it would be hard to hide the fact to the cow that any direction would be down.
Another pratical joke involved the use of outhouses. Once the target has established himself you take up the slack on the attached rope which has been measured to set up tremendious harmonics in the structure. When the rope transfers your strumming to the outhouse, it usually falls apart with a most revieling nature..