You put your card in.
The card is not read correctly by the machine and it is not ejected either.
Someone sidles up to you, asks if there's a problem and suggests you enter your PIN.
They watch you do this.
The card is still not ejected so you have effectively lost the card and walk away.

What has happened is that the cash machine has been nobbled. A plastic strip has been looped inside -

the card slot and carefully secured around the edge of the slot with an adhesive fake surround.

When you leave they peel away the surround and pull out the loop together with your card. Oh, and
they also have your PIN.

Obviously it's daft to enter your PIN in the first place but even without that they still have your
card and it's probably a Switch card too.

Hope this saves someone a *lot* of trouble.

Cheers,

Martin.