So theres a pirate, right? Hes fighting and hes like a captain right? And he has all this crew and hes like Oh yeah, Im a hero! And then so like one day, hes in a battle and then he goes Shipmate or whatever, bring me the red shirt! And then uh he wears the red shirt and he goes into battle and then after the battle they win right? Cause hes victorious. And then the shipmate persons like Oh, why did you ask for the red shirt? And then the pirate guy was like Oh cause when I get stabbed I dont want anyone to see the blood on me or whatever, you know? And then he does blah blah blah. And so yeah, he does that like all the time right? Ok. So then time passes. He hears like all these kings are tryin to like take revenge on the pirate so theyre sending all these troops over. So one day, hes on the open sea and then he sees all these ships. And then uh, hes like Bring me my brown pants!!! Cause hes gonna shit his pants! Isnt that funny? I heard it from my friend I think its funny because, um, you think the storys gonna end in a heroic moment. However, he poos he deposits his fecal matter in his pants and tries to hide it with brown pants. I believe that is very funny. Its one of my favorite jokes I think its funny. Yeah, it talks about fecal matter.
I agree with Kazuma that its probably the surprise element at the end that makes the joke successful in being funny. Based on the setup of the story, the audience is expecting a heroic story with some sort of noble or glorified ending. Instead, it brings up a taboo subject that most people dont really talk about: feces.