Droste effect

Droste effect
 n.— «At my grocery store I could only find three examples: Land O’Lakes Butter, Morton Salt and Cracker Jacks. These packages each include a picture of the package itself and are often cited by writers discussing such pop-math-arcana as recursion, strange loops, self-similarity, and fractals. This particular phenomenon, known as the “Droste effect,” is named after a 1904 package of Droste brand cocoa.» —“Droste Effect Packaging” box vox Apr. 12, 2008. (source: Double-Tongued Dictionary)