Go find yourself a brahmin who is neutral to you, aka not trying to murder you, and crouch down. Go to the side of the animal and press the "use" button (A on xbox 360) and enjoy! I thought this was hilarious and after consulting the wiki you can apperantly do this in Fallout 3 as well. Go try it out, you get a unique annimation and the Brahim will be just fine. At least on the first shove, not sure if you can tip them to death lol
