An "impromptu decision" is a choice or action that is made quickly and without much planning or preparation.
Sentences with «impromptu decision»
While no trade or investment is a guarantee, knowing what you own and why you own it will help you resist the urge to make impromptu decisions and ride out any downturns. (m1finance.com)
With the exception of some brief anxiety following an impromptu decision to cut his own sideburns (why?!) (domesticate-me.com)
This can lead to an emotional response to that boredom by making an impromptu decision to drive thru the nearest McDonalds for a Big Mac. (fitandheal.com)