waste sb's time; meddle with no sincerity; give sb trouble by raising his expectation only to disappoint him; ask (a shop assistant) for this and that without making a purchase

spend time in fruitless activity; fool around for nothing

(slang) to mess others around for no reason; to insincerely meddle in other's business; to make trouble for others by interfering into their matters; fool around; putter about; work to no avail