Borderlands

To get the Green Thumb quest, fast travel to the Middle of Nowhere Bounty Board. Get a car from Scooter's and drive to the right. Notice the small shack with big plants around it. Talk to the man leaning against the shack tp get the quest.

The Boomstick weapon's description is "Beyond groovy", which is a reference to Ashley's shotgun in Army Of Darkness.

The "1.21 Gigawatts" achievement or trophy's description's name is a reference to Back to the Future.

Make sure you're in a fight with more than one enemy and your health is extremely low (10-20). Activate Berserker just before you enter Fight For Your Life! Mode, then kill someone to gain a Second Wind. If done properly, you should be able to run as fast as Brick can in Berserker mode AND you'll be able to fire your weapons. Note: you're not able to sprint while using this, but why would you need to anyway? Activating his Berserker mode again and finishing it, OR dying will cancel the effect.

Successfully complete the game to unlock New Game+ mode. In your second session, all the enemies will be very powerful.