"Happy Mother's Day, guys! Far out!"
Joe, why are you wearing hippie clothes?
"It's Mother's Day! Tis the season to be jolly! Where's your costume?"
People don't usually...wear...
"L'Shanah Tovah, brother. I have a dream."
I don't think you understand holidays, Joe.
(No, but seriously, I have no idea why Joe Maddon is dressed like a hippie on Mother's Day. The answer might just be "because he's Joe Maddon.")
Update: Maddon is kicking off one of the Rays' signature themed road trips with his hippie attire. I'm still going with my original interpretation.