|Yes, that's a mammoth.|
There's a Dwarf, in Stormwind, the size of Deathwing, and it's a legitimate item doing it.
Say hello to Fras Siabi's Barely Bigger Beer. It's been in game for a while but, looking at Wowhead in the last few days, some bright spark's found a way to stack it to monstrous proportions. Needless to say, I reckon this will be hotfixed pretty soon, so if you want to take advantage of it, I'd move fast :D
Proof, if it were needed, that we could really do with some new content very soon :D
EDIT: Thanks to Zable on Twitter (@ZableKynbiir) for some additional shots of the potion 'in action':
Thanks for the pics, Zable!