Gleason devised the Wug Test as part of her earliest research (1958), which used nonsense words to gauge children's acquisition of morphological rules—for example, the "default" rule that most English plurals are formed by adding an /s/, /z/, or /ɪz/ sound depending on the final consonant, e.g. hat–hats, eye–eyes, witch–witches. A child is shown simple pictures of a fanciful creature or activity, with a nonsense name, and prompted to complete a statement about it
Like @lessthanluigi said, I bet all surviving vinyl shops look the same