Safe and Sound
Kill Sanctuary squatters: 0/25 (optional)
Pick up lewd pictures: 0/3
Bring pictures to Marcus -OR- Bring pictures to Moxxi
"During the assault on Sanctuary, Marcus's personal safe was blown out of his store, landing somewhere outside the bounds of the city. He has asked you to go to Sanctuary Hole so you may return the contents of his safe to him."
After locating the safe in the Caustic Caverns, a giant crystalisk named Blue will appear. Blue differs from normal crystalisks in that he can generate juvenile exploding crystalisks that can pursue characters into places where he can't follow. He also has a ranged shock attack that can ravage an attacker's shields in short order. After safe is opened, both Marcus and Moxxi send transmissions asking that the pictures found inside be returned to them. The pictures can be turned in to Marcus for the Lucrative Opportunity, or to Moxxi for a variant of Miss Moxxi's Heart Breaker.
"You handed over the lewd pictures of Moxxi and, in so doing, discovered that there is at least one thing -- or, to be anatomically accurate, two things -- that please Marcus more than turning a profit."
If you turn it in to Marcus you get the relic "Lucrative Opportunity" that gives +29.5% to the Shop Timer Rate (making the shop specials count down faster).