There's little doubt that cow tipping is somewhat suspect. Wikipedia makes it pretty clear that the practice of knocking over sleeping bovines isn't automatically credible.
What bothers me is how a vicious rumor like this got started in the first place. Who has such animosity toward cows that they would even suggest trying to push them over for no reason? Cows are so docile and in some cases, delicious. They don't really deserve to be knocked over.
I'd understand if someone suggested 'Rat Tipping' or 'Snack Tipping' as these animals are somewhat distasteful. Go ahead and shove a sleeping rat on it's rump. Flip a snake on its scaly back. That's not going to bother anyone.
In fact, I'd like to, in defense of the hapless cows, suggest an alternative exercise. Lawyer tipping.