Quest 8: "Jo is suspicious of the Slags. Find out about the dead bodies at the Ghost Farm and find out what happened to Karl." will immediately show up on the Pip-Boy 2000 unless you the player says to Jo, in the same conversation, 'I want to take no further part in this', for 700 XP.
"People will then act a little weirdly: traders and townsfolk in Modoc will talk as if there's going to be a deal with the Slags, the Slags act as if they're waiting for it to happen, and Jo won't talk to you again at all. After 31 days Modoc will attack the Ghost Farm; see the next quest for details.
Whichever way you choose to deal with the Slag matter, from this point on Rose will allow you to rifle through the lost and found box and give you free omelets whenever you want them, but you won't be able to order any of the other stuff any more. The lost and found box is sometimes empty and sometimes has random items: knives, throwing knives, stimpaks, 10mm JHP, a leather jacket or a 10mm pistol. On very rare occasions (1 chance in 200 every time you enter the map) you can find a 10mm SMG in there. If you're impatient you can exercise your Steal skill on the box, and due to what must be considered a glitch you can loot it freely if you stand on the hex just to the right of it.
Characters with an Intelligence less then 4 will earn 2000 XP upon delivery of the note and trigger the happy ending for Modoc but do not get quest 8. You also get a discount on Jo's stuff, but only until you leave dialogue." - Per Jorner, The Nearly Ultimate Fallout 2 Guide