This is a very simple exploit:
Code:
Step 1 Queue for a BG which has very low waiting time
Step 2 Start the Brew For Brewfest Daily, in which you have to ride to carry barrels to the Questgiver as many times as you are able to bring to him in only 4 minutes
Step 3 Do the Quest and receive your Brewfest Prize Tokens
Step 4 At about 1 minute to 30 seconds left on your Mount Buff Timer join the BG
Step 5 After leaving/losing/winning the BG notice your 4 minute Mount Buff Timer
Step 6 Repeat Step 1-5
Step 7 Get your Brewfest Items and Achievements
Good luck!