図工に必要？

My son asked me to save some toilet roll cores.

 I thought they were for his art class so I gave some to him.

息子が、「トイレットペーパーの芯を残しておいて・・・」というので、

てっきり図工の時間に使うんだと思い、せっせと残して渡したところ・・・

A few hours later, it turned out that they were for making 

fake "P...." 

Of course, it has nothing to do with his art class at school....

友達が、

「濡らして、丸めると、

”う〇〇”みたいになるって教えてくれたんだ～❤」

だって・・・