A fork of Rural Dictionary
As Alex (or Alexander/Alexandra) is a given name to many great people, it is natural to pass their shining onto other parts of life. Alex-whoop is to use to express a great achievement or joy/pleasure which is more intense than a normal whoop can cover. The expressing person or others involved do not have to be named Alex/Alexander/Alexandra.
Person A: I finished my competition 1st place! Person B: Alex-whoop!