unplanned
unthoughted
on impulse
intuitive
spontaneously
rock up
on the hop
unconsidered
involuntarily
instinctive
unrestrained
unweighed
catch
blurt out
on the fly
induced
by accident
automatism
extemporaneously
unpremeditated
unscripted
off-the-cuff
think
reflexively
strained
ultroneously
unanticipatedly
unstudiedly
find oneself
throw
off the top of one's head
spur-of-the-moment
impulsive
knee-jerk
unforeseenly
semispontaneous
unpremeditatedly
unprompted
ad-lib
abruptly
automaticism
suddenly
dead
on the spur of the moment
of a sudden
predetermination
short
all of a sudden
all dressed up and nowhere to go
prefiguration