Photograph from Wikipedia
Flessenlikker = "jar licker" in Dutch. Also known as a flessenschraper ("bottle scraper"). The long handle and flexible rubber spatula at the end do just what you think they would: help you get every last scrap from the bottleespecially long, narrow vessels.
The joke here is that it's a Norwegian invention that has failed in every country but the Netherlands.
The Dutch are smart, though: They probably get at least one more PBJ sandwich out of their respective jars than flessenlikker rejectors.
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