The number "3343" could refer to a variety of things: a house number, a date (March 3, 3343, if we were in a futuristic timeline), a reference number, or even a code.
This specific numerical quantifier changes the tone entirely. "4 Girls" suggests a specific grouping. It creates an image of a gathering, a team, or a target. In internet culture, numbers like "4" are often used to title specific episodes of web series, or to denote specific challenge groups (e.g., "4 Girls 1 Challenge"). It narrows the scope from a general concept to a specific event involving four individuals. Moscow Peter Boil 4 Girls 3343