We have it on a recording of the Highwoods String Band (don't know if you can still get it, but if you can, it's amazing!) Here are the lyrics I remember, although from your discription this sounds like this may be a different variation:

Said the barnyard rooster to the barnyard hen,
"Well, you ain't laid an egg since the Lord knows when."
Said the barnyard hen to the barnyard rooster,
"Well, you ain't been around as often as you used-ter."

Chorus:
Oh, who broke the lock? I don't know!
Who broke the lock on the henhouse door?
I'll find out before I go,
Who broke the lock on the henhouse door.

Said the barnyard hen to the rooster out West,
"You know, my dear, I love you the best."
Said the barnyard rooster, "You're tellin' me a lie
"Cause I saw you flirtin' with that old Shanghai."

There's another verse I can't understand about "I thought I heard Ol' Bruno sneeze"--maybe that one's about someone sneaking around in the barn, as you suggest? I'll see if my husband knows that verse (if the knowledgeable folks here don't fix you up first). Good luck!