Rather a damaged slide, I'm afraid, with a lot of dust / mold that wouldn't rub off. Sorry.
But what an image ! A brace of brave boys, bareback on a big bucking buck bunny.
I suspect that this dates from the very early sixties, and could be from Hulstead's Wall Drug Store, as featured in this early blog post. Heavens - was that really two years ago?
Bonus - Brian Blessed advertises Japp bar ?
Engineering Bonus - Abandoned Russian Space Centre