Well, the first time I heard about it was from my Classical History professor, explaining why Hannibal's elephants ceased to be effective after awhile (the Romans learned all they had to do was hold their line). And then I came across it again in the Worst Case Scenario Survival Handbook: Extreme Edition. "How to Survive an Elephant Stampede"

But, if you try it, and it doesn't work, don't sue me! ;-)