To apply, or apply something to, in a hasty, careless, or rough manner; to roughcast.
to slapdash a wall
Produced or carried out hastily; haphazard; careless.
In a hasty or careless manner.
Directly, right there; slap-bang.
Van Eyck signed his portrait of the Arnolfinis slapdash in the center of the painting.
With a slap; all at once; slap.