These rules are often formed under the guise of "honour" or "fair play". They also may include statements such as "I only play for fun" or "I don't care, it's just a game".
Scrublord: Why yes, yes I do. May our duel be honourable!
100 of Mr Doodles friends jump out and tear the shit out of the Scrublord
Scrublord: WTF THIS IS NOT FAIR YOU HAVE NO HONOUR YOU MUST BE A 8 YEAR OLD KID WITH NO FRIENDS AND YOUR PARENTS HATE YOU THIS IS JUST A GAME I DON'T EVEN CARE AND I'M NOT EVEN CRYING IRL RIGHT NOW, HONESTLY, I'M NOT.