When I was a kid in Newfoundland, we said the Lord's Prayer every morning at school. (It was a secular public school, but derived from the Protestant half of a historically denominationally organized school system; old habits die hard.) I knew 'art' was a verb, in 'Our Father, who art in heaven', but I understood it as some verbal counterpart of the noun 'art', as in skill, work, magic, the opposite of the 'dark arts' -- you know, arcane, mysterious art. 'To art' in this sense would mean something like, 'to work (magic)'. So I thought we were intended to be addressing 'Our Father, who works (magic) in heaven...' It wasn't until much later that it occurred to me that this was in fact just an arcane, mysterious form of the verb 'to be'.Sometimes, kids comprehend the darndest things.
A similar example is in mishearing that portion of the Pledge of Allegiance as "and to the Republic, where witches stand, ..."