Why is 5m a swear word?

Somebody at Rito games is a Jhin main and cannot stand the number 5.

Perhaps someone thought you were calling them a cock, penis, or dork. "1. The blue whale's penis, or dork, is the largest that ever existed. The average size for an adult male is 5m (15ft)." http://www.urbandictionary.com/define.php?term=Whale%20Cock%20%28Dork%29

5m, short hand for 5mm. They know your plans.

Hm.

[zombie-brand-clap]

And I thought it was strange when it censored 'crap'...

No idea what 5m could mean.

what is 5m?

Same reason why "suck" is a curse word.

Sticks and stones may break my bones but words are triggering and are banworthy

the hell is 5m... lol.