Excellent idea

You wanna get stabbed over a melon? This is how you get stabbed over a melon

This is something I'm going to have to try at least once. Just grab one thing out of one strangers cart

Hasn't Impractical Jokers done this before?or at least something similar

Focus on one person over several weeks... If there's someone you see regularly at your local supermarket, take random items from their cart only. Every time they get home...
"I'm sure I bought toothpaste?!"
"Fuck. How am I supposed to make Friday night pizzas without cheese?!?!"
"I'm losing my mind"

@kakaburra Do you keep your heart in your grocery cart? ;)