I am now sans undertale

A rare occurrence of a living creature changing its eye color (only the left one) to blue or putting a blue object in front of their eye.

The meme is popular thanks to its simplicity: the "Sans" NPC in the game of "Undertale" can change one of his eyeballs to become blue.

"Ayo bruh why your eye blue???"
"I am now sans undertale"
"Haha funny joke now let's go visit the hospital bro..."