on the fly Synonyms

on the spot unthinkingly at a gallop off the top of one's head hurridly on the spur of the moment without preparation without rehearsal as fast as one's legs can carry one at full speed at breakneck speed at high speed without thinking without consideration a mile a minute without planning in a spontaneous manner automatically on the hoof on impulse extempore impromptu impulsively instinctively involuntarily offhand spontaneously ad lib unrehearsed at full tilt at the drop of a hat unconsciously extemporaneously improvisationally on a whim without premeditation