OFL

Tagging

Probably the most consistently agrued-about thing at an OFL game is the tag. This is why a legal tag is important.
Tags must be two hands to the body. Not fingertips; not to a piece of shirt or the ball. Two hands to the body.
The defender -- once he's made the tag -- should then loudly say "I Got Ya!" or "Down!" or something. Yelling "I Got Ya!" before actually tagging a ball-carrier is not cool (yes, it happens a lot..) The play stops when you announce "Got Ya!" or "Down!" Therefore if you say it before you actually get the ball-carrier, you're cheating. Illegal (phantom) tagging is a 15-pace penalty from the spot of the foul.

The Pass Rush

Defenses count to "Four Mississippi" before crossing the line of scrimmage - unless:

• The ball leaves the quarterback's hands - to pass the ball or hand the ball to another player.
• There is downfield blocking by the offense.
• There is a fumble in the backfield or the snap has been muffed (the ball hits the ground or is dropped by the quarterback during the hike.)
• The defense calls a blitz.

In these instances the defense can cross the line of scrimmage immediately.
Note: "crossing the Line of Scimmage" means any part of the body going over the line. Therefore reaching over the line to tag the QB before the "4 Mississippi" count is not allowed.

Drawn Offsides

Defensive players who've been drawn offside by a fake hand-off or (if blitzing) by a phony snap count can retreat back across the line of scrimmage and reset while the play continues without penalty. If the defense does not reset, an offsides penalty will be called.
Defenses do not have to rush the quarterback (they may choose to double-team a receiver instead), however they must audibly count to "4 Mississippi" anyway so everyone on the field knows.
The "4 Mississippi" count can be quick but it must be audible across the whole field.

Chucking:

Defenses are allowed one "chuck" of the receiver, using open hands to the body, to hold up the receiver. This can be only be done within one pace of the line of scrimmage (not 5 yards of the line, as in the NFL.)

The Blitz:

Defenses are allowed one blitz per four downs. A blitz allows any number of defensive players to charge in without first counting to "4 Mississippi", as long as someone audibly shouts "BLITZ!". The player blitzing does not have to shout, but at least one defensive player on the field must shout it. Blitzing without yelling the word "BLITZ!" is a penalty.
Fake or phantom blitzes are legal. Defenses can yell "Blintz!" or "Bits!" or "Shlitz" without actually blitzing (beer references are encouraged) in order to scare the offense into doing something stupid. Additionally, the defense can yell "Blitz" and not rush in, although they then lose their blitz for those four downs. Essentially uttering the word "blitz" constitutes the use of the blitz play.

Touchbacks:

Touchbacks are spotted 15 paces from the goal line (at the first cone).

Other Stuff

Defending 2-Point conversions and X-Point Plays

On 2-point conversions, the defense can run back a fumble or an interception for 2 points.
No blitzes are allowed on 2-point conversions or X-Point Plays.

Important Note:

The defense is responsible for collecting the ball and the scrimmage marker at the proper spot after the ball carrier has been downed. Purposely delaying this action during a "hurry-up" offensive series will be a delay of game penalty. An un-sportsmanlike conduct penalty will be assessed if the spotting is continually delayed.