Check out the 'Throwing a Screwball' link on this page to find out about the mechanics of throwing a screwball.
Since there seems there isn't a link i will explain it for you. I used to throw it a lot. But what you do is you hold it like a four-seam fastball. What you have to do after this is you must pronate your wrist. Which means you twist you hand, wrist, and forearm counter-clock wise. This will give the ball a spin that will "chop" the air to the right of it (if its a RHP, and vis-versa if its a LHP) causing it to move that direction. But beware, it is a potentially harmful pitch, especially if done wrong! Use it sparingly! If you feel pain, then stop throwing it!
Check out the link below on tips for throwing a screwball: http://www.ehow.com/how_3186_throw-screwball.html
You hold down "A" whilst pitching.
If you hold down "A" when bowling you will throw a screwball, if you hold down "B" you will throw a curve ball and finally hold "A and B" at the same time to throw a splitter.
They are the same. A screwball will break to the right from a right handed pitcher and to the left from left handed pitcher.
A screwball in baseball is a pitch thrown in the opposite direction of a curveball or slider. A right-handed pitcher who throws a screwball breaks from left to right, vice versa for a left-handed pitcher.
Fastball and Screwball, I dont know what else he threw atm
fastball, curveball, screwball, and splitter
Carl Hubbel, not the astronomer! He played for the NY Giants, If I remember well.
The Screwball was created on 1943-02-15.
Screwball Comedy was created in 2002.
A "Screwball" is thrown by a right-handed pitcher, with the holes facing the the left. It is hard to throw a Screwball with a brand new wiffleball, so experiment with scuffing the ball on concrete or sanding it with sandpaper. To throw this pitch you will need to supply a decent amount of force (40+ MPH) and keep the holes spinning completely parallel during the flight of the ball.
Depends on your age, but under 20ish especially, I wouldn't recommend throwing that pitch.