The Allah Visa Swipe is a sexual manouvere referring to Asians immigrating into Europe illegally. It is when the male of the relationship excretes onto a plastic card, often their Visa (hence the name) and then swipes it between the breasts and bottom-cheeks of the lady (or man). It is a way of visually representing the way immigrants take the piss (or shit) out of our country and take advantage of how desperate we are, we actually let them shit on our society and then rub it around by telling their friends and family back home, thus spreading the shit everywhere.
The man running the corner shop receives a payment via visa, however the PIN code checker is not working so in order to make sure the visa is legal (possibly ironic) he pulls down his trousers, takes a shit on the card, and swipes it down the lady's clevage. She just got Allah Visa Swiped.