Quickest Knight checkmate

I don't actually know if anyone has posted the solution for the quickest knight check mate, but I have a checkmate in 4 moves. If anyone found a quicker one, I'd love someone to show it to me.

This challenge was from a posting from IM David Pruess on Chess.com TV

Black can do it in three moves:

Here's one in three:

1. e3 Nc6 2. c3 Ne5 3. Ne2 Nd3#

Ok, so I cheated a little. The rules didn't say who was to mate. I think it's impossible for white to mate with a knight in less than four moves. Black needs to move two pawns and block the king/queen/bishop with a knight. That makes three black moves so white can't mate before move four.

edit: I see OBIT beat me to it. :)

What about fastest rook checkmate?  I found 6:

But I'm sure there's better.

Oops, missed a five.

Ah, nice work David, I never thought about just tearing through the file.

bishop checks in 3

why do I keep coming into these threads?

Woah, nice one, tonydal!

tht King mate is cool!! How in the world did you think it out...

Wow damn sweet. And your name is perfect for it too even has an 8 on the end.

is it a joke?

a-pawn (OK, so maybe that's a bit of a stretch to do specific pawns).