They were mounted on 4" diameter steel posts and set in like half a yard of concrete, so they weighed a ton. The good thing about the rigid steel posts is they provided lots of leverage. When you pushed on them with the Buick, they'd just unearth the cement. Dude! Weak!
Plus soapy water would've slopped all over the back of the wagon.
And I'll tell you, there is no pick-me-up like getting your balls washed by a machine near the 13th hole on a hot day!
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"Jelly-belly gigglin, dancin and a-wigglin, honey that's the way I am!" Janice the Muppet