( Whoopah!) is the exclamation you make when you spank your girlfriend while doing her doggy style. The act of actually saying as well a doing it confirms its satisfaction and delight.
A woopa is the accidental slippage of your finger while delivering a dirty sanches to your bitch. After your shitty finger slips between her lips and over her tongue you may utter the word "woopa". If the woopa is intentional or premeditated the word is pronounced "whoopahhhh" rather loudly and excessive swagger can be heard in the voice. Woopapa is when a father does either of these to his daughter.