<human>: Can you summarize the given text in a few sentences?

This didnt happen to me but to a friend, I had to post it though because the story is too good to be left untold to the internet. (I will be telling it from his point of view to add to the atmosphere.) 

My girlfriend invited me to her house last weekend because her parents were going to leave on a trip to a luxury spa about 100 km away from our town. So in order to fully relax they would spend the whole weekend there. I arrive at her house about half in hour before they leave so I go inside have some coffee with them and all in all it is looking like it will be a fantastic weekend for the exchange of bodily fluids. Her parents leave and we are left all alone. Being the young and daring people that we are we immediately start kissing on the couch in the lounge, we start going further in and soon our clothes are off and we are both completely naked in the middle of the house. She tells me she wants to take it in the ass. Excited, I run to her room to grab some body lotion for an easy entry. I get back and smear her ass with it and proceed to fuck her ass with the force of a miuntain goat ramming a wall repeatedly so I got that shit really shaken up. About 30 minutes in we are still going at it and all is well until (yes the inevitable "until") we here the front door open. Her dad had come back because he had forgotten his wallet, instead he came back to see his daughter being fucked in the ass. I panic and pull out in an effort to apologise to him. As I pull out leaving her ass wide open and lo and behold a massive waterfall of shit explodes out of her butt covering a good portion of the couch and my feet. This was too much for me and I bolt out of the house with only my t-shirt in hand and a trail of shitty footsteps behind me.
<bot>: fucked gf in ass, dad came back, I pulled out, she shat on the floor, I ran away with a trail of shitty footsteps behind me.