a corps perdu
abruptly
at half cock
bang
capriciously
chaotically
dash
erratically
every which way
hastily
head over heels
headfirst
headforemost
headlong
heels over head
helter-skelter
higgledy-piggledy
impetuously
in a rush
inconsistently
inconstantly
irregularly
like a flash
like a thunderbolt
nonuniformly
of a sudden
on short notice
overhastily
oversoon
plop
plump
plunk
pop
precipitantly
precipitately
precipitously
prematurely
quickly
rashly
recklessly
sharp
slap
slap-bang
smack
spasmodically
sporadically
startlingly
sudden
suddenly
surprisingly
impulse
impulsion
impulsive
impulsiveness
impulsor
compulsively