soreloserism 

When you accept the rules of a game, riddle, or challenge, but then instantly back out of the consequences when you lose or fail miserably.

Matt agreed to the rules of the FB riddle, but his soreloserism went on display when he refused to change his profile picture to that of a llama.

soreloserism by @nobody December 15, 2016

soreloseritis 

a disease characterized by being bitter and angry after your favorite couple loses a competition SORE-LOSER-itis

Kelly Monaco fans have a bad case of soreloseritis since John O'Hurley(the true winner) won the Dancing with the Stars Dance Off.

Kelly has a bad case of soreloseritis since she couldn't even clap for John when he won the dance off.

soreloseritis by krazykookyketchupgirl September 28, 2005

Sore Loserism 

A state of mind that prevents those suffering from it to be able to understand logical facts.

A state of mind after a big loss

“Trump followers have been suffering from sore loserism for months now, the Clinton fans got over it within days and got to back work”

Sore Loserism by BlueLJ June 7, 2021