Kookie is pet-name, or nickname for Jungkook, or JeonJeongguk, a member of a KPop band called BTS (Bangtan Boys). Jungkook is the maknae, or youngest of BTS, and adored by many.
When IPhone takes Koolness. Smokes a little weed. Tjen gives You something like what just happened. While I was typing this. Then becomes tjen. Oh you might want a kookie if you are high.