Is it normal that i got off on my friends huge poop....twice!

Ok.This isnt short but informative. A female friend of mine has always been odd when it comes to pooping. She would never go in public restrooms. She'd hold it until she got home. Well one night we went to the movies and she got the urge and she started sweating and said we needed to go. Hesitantly i took her back to my place and she ran into my bathroom. Of course I then figured it out and was kinda arguing through the door. She came out and told me "you'll see why" and she left. I went in and it was so big..I instantly got an erection. I had to get off. Then i tried to flush it and it wouldn't go down. Once all the water went down and i could see actual size i got hard again. I NEED to see this again. Any ladys poop big like this?