Complete gibbering idiocy, like forgetting one's own phone number in a crisis.
The argument about whether his tax cuts are a promise, guarantee or strategy made him look like a gibbering idiot.
Or, of course, he's just a gibbering loon.
Paul's gibbering with some students, Victoria's somewhere in Islington, and the usually unflappable Dave is tearing his hair out.
Whether they end up a fighting machine or a gibbering wreck ' ' Or a corpse.