A moment where her tweaking of your nipples would pinch just a bit harder.  This is in conjunction with your tail violation of sodomizing her.  As it plowed into her tight anal canal.   Her splinter muscle instinctivel clenching around the metal tail.  It is painful for her, but with the cock filling her.  It heightens that experience to no end.  Driving her wild with getting off.  It brings on her own orgasm in response.