Birmingham-based artist Foka Wolf – who keeps his real identity a secret, à la Banksy – is best known for his spoof out-of-home advertising campaigns: perfectly passable and unremarkable at first glance, scorching satire on closer scrutiny.

There’s been the mock Conservative Party ad – stuck up in London Underground carriages – that read “We plan to cut all homeless people in half by 2025”. And a Pepsi poster that features an image of a condensation-coated can and the tagline “Get some diabetes water down ya”.

Having taken on the government, brands, energy companies and drivers of “big stupid cars”, the mysterious artist has now set his sights on the supermarkets – specifically Tesco – with two new works.

The first takes Tesco’s logo, font and shop sign design guidelines, but adds a highly unlikely bit of corporate copywriting: “It’s OKAY to shoplift from us if you’re broke. We still make a profit.”

Given retail profits at the supermarket rose 11% to £2.76bn in results released last month, he’s at least half right.

But it’s the second Tesco-spearing work that could have executives concerned. It takes the form of a shelf-edge pricing label – again with the correct fonts, graphics and sizing – except the discount goes beyond anything Clubcard might offer. “£0.00 Free, Five finger discount,” it reads.

Foka Wolf has offered the labels as a free PDF download and produced a video guide on how to place them in stores. Just a prank or making a serious societal point?