(adv.) With the head foremost.

a corps perdu bang bearishly bluffly bluntly boorishly brashly brusquely cavalierly churlishly crustily curtly dash forthwith gruffly harshly hastily head over heels headfirst headforemost headlong heels over head impetuously impulsively like a flash like a thunderbolt nastily of a sudden on short notice plop plump plunk pop precipitantly precipitately precipitously rashly sharp sharply short shortly slap slap-bang smack snippily startlingly sudden suddenly surprisingly unawares unexpectedly without notice without warning