Junereth

perhaps it happened to some jap dude when he was looking at porn in a bookstore, and some mangaka found it hillarious :P

Lead

I am not sure on the origins on it but...
It might have been an occurence with japanese people when their diets didn't consist of much iron and such, when they got excited, or got a large rush of blood to their heads (I mean anyone knows they go red in the face when they are embarassed/angry and they have a pale skin tone) could have possibly resulted in a slight nose bleed in some and thus exaggerated for anime purposes for when a guy got excited/embarassed after seeing something sexual.

I dunno, just a theory on my part.

PrashT

Well, in my case, I did once.

Once upon a night, after I come back from campus activity(Otaku related), I watch Ikitosen that I borrow from my friend. And then, after few hours I smell sumthing strange, and when I almost put my hand onto my nose, sudenly.... What the it's bleeding.

Dont know if it b'cause the Ikitosen factor or the other factor. BTW I feel realy tired that night, not yet eat my dinner and forgot my breakfast ><

Or maybe the nosebleeds is just for Japanese or asian people maybe, dont know with the europeans or americans, or maybe a genetic factor?

ShiroTheGreat

I don't think it's possible. Perhaps you've been watching too much anime. lol. And like Koinuboy said, A LOT of people might need blood transfusions. Haha! But wouldn't it be weird if that really did happen tho? I recall seeing a movie where they brought that gag to live action... it seemed weird. lol.

emeraldnite99

I remember my nose bled at times for no reason, so I guess anything is possible. I particularly remember having no bleeds during a hot shower, so maybe being horny and getting hot in the head relate to nosebleeds somehow. Or maybe it is like American cartoons where steam comes out of a character's head when they get hot and nervous, but the Japanese make it more realistic and blood comes out instead.

LenasLover

The public school system could help. They could serve low fat healthy foods only. Fruits & Veggies.. some decent food so kids don't just pig out on chips and cookies and pizza like I used to in school. And gym class is a joke. I graduated high school in 98- and I can't count the number of days we played board games in school. Board games. That's not exercise. Gym teachers should make kids run and play sports. Sure, kids with physical conditions should be exempt- but on the whole, the school systems could be doing more since parents obviously won't.

Orkbert

No, we don't get nosebleeds. the blood rushes somewhere else in this situation (...)

Of course someone with hypertension and fragile/weakened blood vessels in the nose might get some of them ruptured when his blood is rising due to seeing something, ahem, pleasant...