10. Rakkman Returns?
After you kill Laney during the Cold Shoulder quest, head inside her vault and follow the path deep inside until you get to a lift. This will take you up to The Rakk Cave, where the Narked Knight, Rakk Man himself waits. He poses a bit of a challenge, but he's no Bruce Wayne and should fall without too much effort. When he does, he drops the Gunnerang, a scoped gun that becomes a boomerang whenever you reload it.
11. Caustic Souls
Want to find the Dark Souls Easter egg? At the far east of Caustic Caverns is an acidic lake, and in that lake is a small island. Any Dark Souls fan hardy enough to brave the caustic conditions to get there (and if you are a true Dark Souls fan, that shouldn't be a problem) will find two nice little nods to From Software's opus. For non-Dark Souls fans, it's just two guys sitting near a campfire, but we know what it means.
12. Picard's Pizza Wisdom
To get the most out of this Easter egg you'll need a QR code scanner of some sort - probably your smartphone if you're all fancy. In the Southpaw Steam & Power area you will find one of Moxxi's pizza boxes on a table. The pizza box itself has a QR code on it, and if you give it a scan, you'll find a delicious, deep pan slice of Star Trek wisdom courtesy of one Jean Luc Picard:
"Wise man say, forgiveness is divine but never pay full price for late pizza. -Captain Picard"