Happy as a what?

kw: folklore, aphorisms

An advertisement that has been running lately ends with the words, "I'm as happy as a woodpecker in a lumberyard." The first time I heard it, I about had to sit down. Perhaps I know too much: A woodpecker would starve to death in a lumberyard. What is a woodpecker after, hammering away on yonder tree? Beetle grubs under the bark, that's what. Bigger woodpeckers such as the common flicker can also get a half inch or so into the wood for grubs that tunnel deeper. The wood in a lumberyard has all been cooked, so any grubs it may have contained are dead and dry as dust.

That got me thinking, what other common proverbs are actually nonsensical? Only one pops to mind: "Happy as a pig in sh*t." I have heard that one here and there in the past, though it is a little less common than "...pig in mud" or "...in slop." These latter two are accurate. A pig can't sweat, so it rolls in water or mud to cool off. But if a pig has room enough, it will never defecate near the mudhole it wallows in. They do have a sense of cleanliness, though it differs from ours, and sh*t is definitely not on their list of favorite ointments.