When you go to wipe your ass and either A) the toilet paper you've chosen to use fails resulting in shit all of your hand. B) Said toilet paper does not exist or C) Somehow shit actually finds it way onto your hand.
Also related: Poop Thumb (Which is a lessor case of above - Shit Hand)
I was in the toilet when my toilet paperripped in half, so I have a severe case of shit hand right now.
Ever have poopthumb? Well I have shit hand, that is a whole other list of problems.
To knowingly or unknowingly shake someone's hand directly after having a shit without washing urhands, the other person might be too embarrassed to sniff their hands after the shit handshake.
"Shit in a hand bag" is an expression used when something unexpected happens.
Much like finding a turd inside of a pocketbook this event is of a great surprise to you.
"Shit in a hand bag! I've lost my keys again!!! Shit in a hand bag!"
To have respect for those who control your manners, paycheck, and just plain the way you act.
Such as.... 1) don't shit in the hand that slaps you as in your parents because they slap you with that hand by controlling your existence. 2) don't shit in the hand that slaps you as in your boss or supervisor because they control raises at review time and promotional futures. 3) don't shit in the hand that slaps you if of your wife or girlfriend because, well, we all know what she does with that hand don't we?