Oh man, don't believe everything that the player says, Professor Oak XD
You, the player, (in this case Pokemon Trainer Red) may choose any name for yourself and your rival.
Your rival in Pokemon Red was basically a douche, so you can kinda see where this is coming from.
The naming-your-rival joke's been done before, this is just my own twist on it.
Sometimes I would name my rivals N00b or something like that while I was playing Pokemon games when I was younger. In Platinum I named my rival "LAME-O" (Sorry Barry)
Oh yeah OMEGA RUBY AND ALPHA SAPPHIRE