Happy birthday! 生日快乐!

Congratulations! 恭喜!恭喜!

You must be feeling great! 你一定感觉很棒!

It's a big day. 今天是你的大日子.

It's your special day. 今天是你特别的日子.

We should celebrate. 我们应该庆祝一下.

Enjoy yourself. 玩得愉快.

Have a super day. 祝你有美好的一天.

I wish you all the best. 祝你万事如意.