Another thing that seems impracticable. People barely look at a car with the alarm going off. Like a squealing wallet is going to prevent a mugger or pick pocket from beating feet after taking it from you.

Better yet, a wallet with a Taser, a die pack in it, and also releases green smoke. See how far the thief gets, curled up and shaking on the ground, covered in toilet-bowl-blue ink, and green smoke pouring off them.

(just remember to grab your phone, when you grab your wallet and keys or you would be that guy in front of your house. )

"Oh look honey, I think our neighbor, forgot his phone before walking out of the house."

"Whys that"

"He's laying in a blue puddle, and green smoke is pouring off him. Again.."