I guess her company or her manager ask her to smile.
Would u be smiling all the time if u are the one. i bet not.
So why people are making things difficult for them. She has a lot of activities which result in her being tired.
hahaha.
She looks so cute over there and her manager is so bad, doing all the prank on her.
i guess her t-ara members would also do so if they are there.