The Mugging diversion can be started by aiming a weapon at a civilian while in Fine Aim mode. After a few seconds, they raise their arms, and the crosshair must be kept on them until they drop some cash and run away.
It is not possible to mug 3rd Street Saints, enemy Gangs, or Law Enforcement. It is not possible to start a mugging with any Notoriety, but since Notoriety can only be gained when the police see Playa Mugging someone, it is possible to do several in a short span of time.
It is not possible to mug someone who is cowering.
It is possible to unlock Mugging rewards immediately after "Jailbreak", meaning that Jane Valderamma is the first Homie who can be unlocked, and it is possible to unlock her before gaining the ability to recruit Followers, although she doesn't arrive if called before "Three Kings".
Drunk Civilians do not raise their arms while being Mugged.
A random Civilian line "I swear I'm going back to school" references the film Fight Club, in which the film's protagonist mugs a person and tells him to finish veterinary school.
If the police witness a Mugging, it is not possible to finish it. Even if the Notoriety star goes away with time, the Civilian continues to stand with their hands up until the reticle is no longer over them.
Quitting Fine Aim mode while mugging gives level 1 police Notoriety, no matter if there are not any police officers nearby.
In Saints Row IV, if a homie or non-recruited Saint is nearby while trying the mug someone, aiming at the person makes the ally shoot at the person and likely kill them. This means mugging is best done where there are no homies recruited or in the vicinity or before taking over the neighborhood.