Not that much. :) You just misspellt "próbáljátok", and a prefix is needed for both of the verbs. Also, to make it more natural, I would use "ez" instead of "az", and I would add "egymás után" ("one after another").

"Próbáljátok meg ezt tízszer egymás után gyorsan kimondani."

Just wait for the actual Hungarian tongue twisters ;) :D Rap fast this line: "Fekete bikapata kopog a pepita patika köveken" (Black bull's hooves are knocking on the chequered floor tiles of the chemist's shop – okay, the scene is strange, too :D but it is a well known one.)