Thanks to my sister Hannah, and also Chris, for this. Hannah found it on some tumblr like 2 weeks ago, and passed along the following context:
Clint Eastwood rides a rare miniature pony on the set of Joe Kidd, 1972.
And then I forgot about it til Chris sent it along like 2 days ago saying:
Wow psamp wow. Make my day mini pony.
This is easily one of the greatest mini ponies we've had on PSAMP. We've had tons of dumb "celebs" like Snooki in pictures with mini ponies, but Clint gives us a whole new level. We're talking an Academy Award-winner, here. Plus, you can use like unlimited Eastwood quote puns:
Go ahead, make my hay.
Get off my foal.
Bout time this town had a new sheriff (UNCHANGED! – ed.)
I mean come on.
