After finishing Defeat the Underpants Gnomes, you will be back in your bedroom and there will be a gnome standing near the hole in the wall. Talk to him and he wants you to steal some underpants for him, since there is a shortage of gnomes. There are five underpants throughout South Park, all of them inside of drawers in houses.
- Kevin Stoley's house is located east of the Community Center, so find that first and then go east to the second house from the left (there's a Fast Travel in front). Go inside and into his bedroom, where you'll find the Underpants in one of the drawers.
- In Cartman's room
- In Kyle's room
- In Stan's room
- In Stan's parents' room
Bring back all five Underpants to the gnome in your room and you'll finish the quest, with your reward being the gnome becoming your friend.