i was searching on IU and i came across this
"I have never understood the purpose of this car accessory.

This site says it “hides cashcard to prevent
theft”, and is available for $6.95
There’s no lock on this device, so if anyone wants to take a
cashcard out of your IU, they simply lift the cover.
This is how it works: you keep your cashcard inserted in your
car’s IU so that you don’t drive under an ERP gantry and get fined
for not having a cashcard in your IU. So, you’re afraid people
might break into your car to steal your cashed up cashcard, so you
put a cover on the IU so that you screw with any would-be thief’s
head:
Hmmm… got cash card inside or not? So hard to tell, with
this stupid cash card cover.
Hmmm… I think got. Because if don’t have, they won’t put the
cover. OK, I’ll smash his window.
Hmmm… then again, maybe don’t have. He’s trying to make me
second guess my decision to smash his window. So maybe better don’t
smash his window.
Hmmm… then again, how would I know if I don’t smash his
window? OK, I’ll smash his window.
Hmmm… if I smash his window and there’s no cash card, damn
wasted effort right? OK, maybe better don’t smash his
window.
Hmmm… then again, if I don’t smash his window, and there’s a
cash card inside, damn wasted right? OK, I’ll smash his
window.
Hmmm… OK, if I smash his window, and there’s a cash card,
but the cash card got very little cash inside… OK, maybe don’t
smash his window…
Arrrrgh! Fuck! I think I go rob some old lady first, then
come back and smash his window.