--- --- --- ---
| | | | |
--- --- --- ---
| |WN |WN | |
--- --- --- ---
| | |WK | |
--- --- --- ---
|BK | | | |
--- --- --- ---
An end game that is virtually impossible and must be assisted by a moronic opponent (or someone who is ready to lose), otherwise known as a helpmate. The opponent's king must be forced into the corner, BUT must move there on the move just before the knight checks it (the other two pieces already being in position). This, of course, is a royal pain (haha) because you must have the kings on the same file, then check with the knight on the right and HOPE that the king moves down instead of up and avoiding this mate altogether.
ie:
--- --- --- ---
4 | | | |WN |
--- --- --- ---
3 | | |WN | | White Knight has just moved to C3. He
--- --- --- --- must now hope that the King will move
2 |BK | |WK | | to A1. This only happens if the
--- --- --- --- opponent is dumb.
1 | | | | |
--- --- --- ---
A B C D
--- --- --- ---
4 | | | |WN |
--- --- --- ---
3 | | |WN | |
--- --- --- --- The black king moves and leaves this
2 | | |WK | | position. The likelyhood of this is
--- --- --- --- slim to nil.
1 |BK | | | |
--- --- --- ---
A B C D
--- --- --- ---
4 | | | | |
--- --- --- ---
3 | |WN |WN | |
--- --- --- --- Allowing white's other knight to
2 | | |WK | | checkmate.
--- --- --- ---
1 |BK | | | |
--- --- --- ---
A B C D
While this is fun to try and do, it just becomes a bit of a pain in the ass. It is fun to toy with newbies though by drawing the game out as long as possible and this is a damn good way to do it. This endgame becomes far easier if the knights have a helper in the way of a rook or bishop. | 
