Quoted this and that by Kat & Satoshi (katnsatoshiinjapan.blogspot.com)
bon bon drop stickers or seals as the Japanese call them are all the rage they are plastic and 3D...made me smile to see the younger generations trading stickers

Back in Newsletter Leaf Journal 269, I linked to an article about Pokémon card speculating which referenced “Bonbon Drop stickers.” Regarding the stickers, I wrote that I did not know what they were. Now, thanks to Kat & Satoshi’s Our Adventures in Japan blog, I know that these stickers “are plastic and 3D” (see their photo).