Leaving The Lid Off The Blender Edit Meaning

1.

To leave the lid off the blender is to invite disaster by rushing into something unprepared. It comes from the mess created by forgeting to check the lid is on properly on a blender leading to the walls getting coated in whatever it contained.

Guy 1: Dude! You didn't revise?

Guy 2: Yeah I know, I'm totally leaving the lid off the blender.

See cock up, screw up, blunder, fail