In the 3rd NES Teenage Mutant Ninja Turtles game you have your standard four turtles to pick from:

which you get to pick from pretty much any time you run out of health.

Now, what if you were at the 'select your turtle' screen and pressed Down on the control pad five times (ten times if you're playing a two-player game)?

You might see the words 'Auto Mode' appear up in the corner of the screen.

Which means that the game will randomly decide which turtle to give you, should you run out of health, which makes the game a bit more interesting.