I've frequently (more than once a year) seen "Free pound of bananas" coupons as part of circulars/loyalty coupons at supermarkets I've been to (sometimes not even requiring further purchase). I've worked in advertising and marketing for checks watch years and am familiar with all sorts of different offer types and sales models. Free or Nearly Free bananas would seem relatively reasonable, and if I didn't frequent the store enough to know they always have a "cute" sign with nonsense prices, I would still be livid if the price wasn't honored.

If you would like links: Here's a 5 year old piece about Amazon giving away bananas: https://www.foodandwine.com/news/amazons-free-bananas-disrup...

Here's a 2 year old coupon for free bananas from some couponing blog: https://www.thecouponingcouple.com/free-bananas/

Another blog, more free banana coupons: https://spoonuniversity.com/how-to/10-food-budgeting-tips-i-...

TL;dr- Don't put up bullshit pricing signs and assume people will understand the "joke", you're coming from a place of different cultural awareness and it will burn you when people like me get involved.