Google qives several quotes.
The book Teaching Poetry by Fred Sedgewick in 2003 says his late grandmother-in-law heard it from one of her pupils.
One of the other Google quotes says "I once heard a 13 yr old boy...."
Sounds like an urban myth to me, it happened to a friend of a friend.

Obviously a memorable quote though, that chimes with what the high-brow think that the low-brow think about poetry.