FTO told me to 'dump the flaps'. What does this mean? Does it mean extend, or retract?
I'm in the US, so take it for what it's worth, but I'd have interpreted it to mean "retract". "Dump", to me, means "get rid of". Now, "Drop the flaps" would mean extend.
Ambiguous phraseology is a problem, but there isn't a standard for everything. I've told students "FULL power" which they heard as "PULL power", to our great dissatisfaction.