why did people at my school take me seriously when I said I was going to the prom with Nate River?

They are all jealous.

Next time tell them you're going with Valentinez Alkalinella Xifax Sicidabohertz Gombigobilla Blue Stradivari Talentrent Pierre Andri Charton-Haymoss Ivanovici Baldeus George Doitzel Kaiser the Third.

It's because they haven't watched Death note yet or simply forgot his name

Also nate river sounds like a pretty legit name if you would have said something a little more odd sounding like Train Heartnet people would of questioned you a little more

Because they probably have no idea what you're talking about nor who Nate River is and probably think that he's HOT and maybe try to steal him away from you, I don't know...

They've never watched Death Note.

Either that, or they were all screaming inside because they were jealous. :)

Hmm...

Maybe because they don't know who N is, or they hate Death Note.

Who's that????