Sex Chickie & Ben
If you recall that episode when that big breasted woman in the Porsche seduces Ben... it gets out that she, whatever her names is, I forget did ALL of the cops at some earlier point.
At one point Chickie says:
"She even tried to get me to do a 'threesome'"
Then she pauses and asks Ben if the woman still as a certain poster over her bedroom door.
In other words, Chickie did the threesome. That is how she knows that.