Interesting... I once had a "second coming" at a parlour (China Health in Portsmouth). I tucked the old chap down between my legs and the girl paid it so much attention I popped while still face down. She then came up to the head end and said in a panicky voice "you still want happy ending? You still pay?!!"
Of course I said yes, so got my second pop - all for £20 and in a 30 minute session. Never asked for a happy beginning though - might try it next time!