somebody is all wet
From Longman Dictionary of Contemporary Englishsomebody is all wetsomebody is all wetAmerican English informalWRONG/INCORRECT someone is completely wrong → wetExamples from the Corpussomebody is all wet• Yes, the point at which we conclude that your reasoning is all wet.• It is all wet and then he had like a side view of it.• I peer into the rain for a glimpse of Storskarfjell, but it is all wet misery to the south.