[grantsrc]

Don't know where the term came from but it is commonly used. Not found in books though.

The concept that I think he was getting at is watching the wideout blocking down towards the TE or T. The WO runs downfield some, and heads back towards the spot of the snap, usually looking for the DE or DT, mabye an OLB. If he contacts him, it must be a clean block, ie. no clipping or block in the back.

Crackbacks are legal, as long as they fit the description of a legal block. Usually HS players don't fully understand the concept of a crackback and block someone in the back.