on a whim

on a whim

Based on a sudden, impulsive urge, desire, or idea; without careful planning or because of a capricious inclination. On a whim, we drove to the beach for the weekend. Major governmental policies cannot be decided on a whim; they have to be carefully and rationally thought through.
See also: on
References in periodicals archive ?
I just happened to turn on that game on a whim and I could tell he had a good strong presence on the ice and that he could grow into that big body.