From Instagram:
xxxibgdrgn: 쇙일쭈꽈홰대쑹
(Happy Birthday Daesueng)
(Note: GD wrote his comment in a cute/childish way to sound sweet and aegyo-ish. It literally sounds like: Shwaeng-il Chuu-kkwa Hwae Dae-Ssuheng)
From Weibo:
GDRAGON_OFFICIAL: #HappyDaesungDay# ✨🎂😁🙏😁🎂✨