[TL;DR] Girlfriend caught a shiny magikarp in less than 20 attempts

Story, she got a new job and its in a nice area and I drove her up there. Instead of going home I decided to go for a walk and ended up finding a neat little river water walk with restaurants and a plethora of pokestops, I told her we should come back after she gets off work.

There were also a large number of magikarp there. I caught 16-17 I think that day. No shinies I figured since I see posts here all the time saying it took 4XX or 5XX catches it would be extremely unlikely I'll find one. Fast forward to that night I met another pokemon go trainer and we were talking and she happened to catch it while we were standing there but she didn't even know what it was! So she didnt say anything.

We started walking away and she said there was something I was going to tell you but I cant remember. Middle of the night she remembers and pulls out her phone and goes is this what you mean by a shiny magikarp..... Im just laying there like wow you have some serious luck.