I caught a shiny Solosis when I accidentally ran into her. I forgot to save 
#What is your worst shiny fail
frosty jasper
thorny harness
It still hurts me to this days… I’m riding Latias in Pokemon Alpha Sapphire right after catching the Kyogre. I go in one of the Hoopa portals and after five resets, a shiny Cobalion appears… and I have 20 Hyper Balls left, no Master Ball and no money.
visual horizon
When i first started Violet I was just walking around, checking out the environment. I see an Oricorio and I think, "thats a weird looking Oricorio." Then I realized it was shiny! Ran up and started a battle. Got it to low yellow, tried to throw a ball, it escapes, and dies to poison. And then I realize, I didnt save beforehand, so now I can't reset my game to try to catch it again. I was so devastated.
fluid garnet
A damn Pidgey in ZA, flew away before i even caught it, sad :(
tropic fern
Do you want one I have 12
fluid garnet
Do you want one I have 12
Oh buddy, i have PLENTY
tropic fern
Okay
lime pond
It was my first game ever(firered) and I fumbled a shiny mankey despite knowing it was shiny
tropic fern
Oh that's sad
silk basalt
My shiny Raticate in let's go eevee, I accidentally released it, my first shiny💔
tropic fern
Nooo that's sad