Solve Phil's Canine Conundrum

Go to the Casino area of Junktown. To the right of the entrance to the area there are a pair of people trying unsuccessfully to enter their house. The reason: a dog.

Simply wear a Leather Jacket (which will remind it of it's former master) or give the pooch some Iguana-on-a-stick to solve the quest and let the couple enter their house unmolested. There is no monetary or experience reward for doing this, you just get the couple's thanks and a pet dog named Dogmeat that will follow you everywhere and has lots of nifty bite attacks in combat.