On the Hellfire Penisula Quest; 'testing The Antidote' You can Spam the Cenarion Antidote you're given and it will enrage the Helboar everytime, (making it into a Dreaktusk - More hp Ap etc...) Quite fun to do it when i saw a mage AoE grinding them, Making them all enraged so she died
[ame=http://www.youtube.com/watch?v=j1etEftOeJk]YouTube - Helboar Enraging[/ame]