Clean and perfectly pressed shirt left in a yucca outside a restaurant.  A story, for sure, but as I walked by idioms about shirts were what popped into my head...

To lose your shirt (to lose all your money)
Keep your shirt on (to tell someone to calm down)
Hot under the collar (angry)
Give the shirt off your back (generosity)
Have the shirt off your back (something/someone is costly)
Someone is like a stuffed shirt (old-fashioned, pompous)
Buttoned-down (old-fashioned, conservative)
White-collar crime
White/blue collar job/worker
To roll up one's sleeves (get ready to work)

I expect there are more

91ºF