My 2 cents.
Fuck your GF from behind and say loudly " Me love you looong time", then hold on to her hair while the bucking commences.
That is know as the Rodeo position.
Seriously tell her it was before she was on the scene , so put or shut up.
This coming from a married man 
, if mine finds out about my punting i 'll tell her to part her legs more than once a decade. 
Let's flip it. What if she says before she met you she saw a few male escorts?
