Guillermo,
"Crow" is when both ailerons deflect upward (yet still continue to function as ailerons). I think it originated with the glider guys who use it with spoilers to add drag and kill lift during landing approaches. They use it almost like a throttle.

With jets, we combine crow with landing flaps, mostly for jets that have excess lift and/or just don't slow down well in the landing pattern. It's very popular with King Cat and Bob Cat type jets. Put them out just prior to or on base leg and the jet will slow nicely while maintaing a normal descent profile to landing.

Craig