That was one of those fun, light-hearted, off-beat novelty songs that were so popular in that era. There was SO much creativity then and the studios produced those novelty songs. There's nothing like that today where every song sounds just like every other song.
"Thinly veiled double-entendre" -- no kidding. "I ride ride my bike, I roller skate, don't drive no car. Don't go too fast, but go pretty far."
And "I got a brand new pair of roller skates, you've got a brand new key. I think we should get together and try them out and see."
Yeah, Brand New Key was an odd, light-hearted follow up to the very powerful, heavy gospel, anthem-like Lay Down, a highlight of the culturally epic Woodstock.