This is a method to earn as many Badass points as you desire on Borderlands 2.

1) Create a new character and have a second player join the game as a guest on controller two.
2) Stand next to your second controller and keep activating a trade.
3) It will still count as a trade even if you don't trade anything, so do this fifty times earning yourself 166 Badass points.
4) Make a new character and do exactly the same as before.
5) This can be repeated as many times as desired and then you can delete all of the characters you created.

Note: This can also be done by defeating the second controller in duels.