The first NPC interaction in Pokémon Blue/Red can remember being a source of amusement for me and my primary school friends.

Professor Oak: "This is my grandson. He's been your rival since you were both babies. Erm... what was his name again?"

Player: types in a silly/rude name

Professor Oak: "Yes! I remember now! His name was (silly/rude name)!"

I also remember the rival saying "smell ya later". I wonder if this was in the Japanese version and if it was influenced by Milhouse from the Simpsons.