Bully the Bully

 refers to an unmarked quest in Fallout 3.

When you ask Princess in Little Lamplight about her nickname, she is less than forthcoming with information about it. If you have freed Sammy from Paradise Falls, talk to him about her and pass a Speech check to find out that she once was mayor, immediately declaring herself the Princess of Little Lamplight. This lasted a whole 5 minutes until MacCready punched her and took over. Ever since, she has had a secret crush on MacCready.

You can now torment Princess with this information, the higher your Charisma the more you can torment her.[Verification needed - seems to be a single, flat Charisma check]

Reward

 * Negative Karma
 * Will no longer speak with you