It is bold and it is really
dumb. Dumbassity is
dumb and audacity inseparably conjoined, in the tradition of "assclown". While something can be done with audacity without being
dumb, and something can be simply
dumb without being audacious. When you have the combo platter, it will likely be spectacular, and perfectly described by "dumbassity”.
I have been working “dumbassity" into conversation for about a year in my social and work circles, and it is showing some traction. It rolls nicely off the tongue.