Longer than you think! I was recently reading up on commedia dell'arte, Italian improv theatre from the Renaissance, and I came across this stock character. To quote from Wikipedia:

Il Capitano often talks at length about made up conquests of both the militaristic and carnal nature in attempts to impress others, but often only ends up impressing himself. He gets easily carried away in his tales and doesn't realise when those around him don't buy his act. He would be the first to run away from any and all battles and he has trouble enough talking to and being around women.

Sounds pretty red pill doesn't it? But wait, there's more! Commedia dell'arte was in turn influenced by ancient Greek and Roman comedy. One of the major stock characters there is Miles Gloriousus, the braggart-soldier:

This foolish Miles Gloriosus brags openly and often about his supposed greatness, while the rest of the characters feign their admiration and secretly plot against him.

So, making fun of red pillers is not something new, it turns out we've been doing it for at least two and a half thousand years (its possible that the Greek stock characters are based on even earlier characters that we no longer have records of). When you laugh at Demonspawn's stained cargo pants, you can now rest easy in the knowledge that Plato, Marcus Aurelius and Leonardo da Vinci would have found it just as hilarious in their time.