A girl, who does not want a relationship, but wants the 'benefits' of a relationships - i.e. money, taken out for meals, etc. However, she does not want to be tied down to one man/sexual partner. This is more than a 'fuck buddy' but less than a full blown relationship (i.e. still will not swallow).
The female will see a guy, Mr. A, on a regular basis, but occassionally on a Friday/Saturday night, will hook up with another guy(s) for 'special time' - a.k.a. The Lawson Effect.