Cornelius has lost his gold pocket watch. Find it and return it to him

Cornelius is Rose's husband in the back of the restaurant in Modoc, likely kept back there because his brain has a few faulty wires. Talk to him and bit and say he needs help, and he'll send you to talk to Farrel, who he thinks stole his watch. Talk to Farrel, he claims he doesn't have it but also asks you to keep an eye out for it.

Go to the outhouse above Farrel's home, and climb down into the cave. Set some explosives near the rock pile, set the timer to max (3:00), and climb out. When you emerge, the outhouse will be gone and Modoc will be a bit redecorated, earning you 500 XP. Climb back down and go to the back of the cave. Kill the Mole Rat and take the watch from its nest.

Now, you can give the watch to Cornelius and tell him you found it in Farrel's home, this gets you -5 karma and 500 XP. He also goes to have an argument with Farrel afterwards, you can go watch if you like, you lied to him so you may as well enjoy the show. Or, you can give the watch back to Farrel, who will return it to Cornelius. This gets you 1500 xp and +10 karma.