Beat Francis at armwrestling.
To try to beat him you'll need a high amount of Strength (9 or 10) AND Endurance of 8+, a bit of luck and be at least level 6. If you don't have these stats, you won't even have the chance to challenge him.
If the player doesn't have the minimum Strength and Endurance needed, they can simply take a Buffout or two. Winning gets the player a power fist, a powerful Unarmed weapon for this point in the game.
If Francis wins, you'll be his gimp for the night, and will wake up at his house with a ball gag in your inventory. Plus, if you are female and have the "Sexpert" perk, all the inflatable rubber dolls in the game will have your name on them, instead of Tandi. (Search the near bookshelf to see it)... The people on the ship in New San Francisco will also mock you and call you names.