Haters Gonna Hate (Season 2)

To earn this achievement, you need the help of at least one friend; the more help you have, the easier it is to do. Your friend(s) must speak to [npc=68792] (as Alliance) or [npc=68794] (as Horde) and buy multiples of any or all of the following: [item=93044], [item=93045], and/or [item=93043]. Each of these 3 items have a separate cooldown, so purchasing multiples of each is the ideal thing to do. They can easily be used in succession if you are throwing different fruits one after another.

You need to enter the queue to brawl an opponent. While in the arena, your friends should use the previously purchased items and throw them at you. You should watch your stacks and time the debuff such that you are at a full 10+ stacks (more than 10 is perfectly fine) before landing a kill on your brawler opponent. Your friend(s) should be aware to keep throwing the rotten food at you all the way to the end to be sure you get credit, as the debuff it provides only lasts 20 seconds.

Do not use any immunity abilities, as this can cause your debuff to be removed. It should also be noted that this achievement is much easier to earn at the lower ranks, particularly on bosses which don't do much damage or have abilities that can one-shot you, as this allows for your friend(s) to be able to get stacks of the debuff up on you more easily, since you won't need to move around too much.

Also, all 3 different rotten foods have separate cool downs. So you can throw all 3 one after each other

SDimou,

To answer your question I was at 22 stacks of the debuff when I was awarded the achievement. So, you do not need to have the exact 10 to get it.