關於「Pen friend app」標籤，搜尋引擎有相關的訊息討論：

PeN Chat™ - App (@pen_chat) / Twittertwitter.com › pen_chatWhat is your review of the pen friend app, SLOWLY? - Quorawww.quora.com › What-is-your-review-of-the-pen-friend-app-SLOWLYPen Pal - Leek Duck | Pokémon GO News and Resourcesleekduck.com › penpalSlowly - Make Global Frie