a sideline cheer
I am a soccer referee and I have never heard that term before, I would imagine it is the sideline.
Line of Scrimmage
A cross.
When the ball leaves the field of play completely surpassing the sideline.
Sidelines are used in American and Canadian football, basketball and lacrosse. A sideline is also used in sports such as soccer and rugby, but they are known as touch-lines.
FIFA does not required side line retrievers. NFHS (U.S. High School) soccer does require them.
Footy or soccer.
An activity preschool can do in the fall is play flag football or sideline soccer.
The ball has gone "in touch" and the restart is a throw-in.
Whichever person touched it last, the opposing team gets it.
look at footballcv.com this is open tryouts with alots of pro clubs on the sideline.