Suàn wǒ yíɡe.
算我一个。
Count me in!
Notes:
算(suàn): to count
我(wǒ): me, I
一个(yíɡe): one
Example:
A:明天我们去苏州,你去吗?
Mínɡtiān wǒmén qù Sūzhōu,nǐ qù mɑ?
We're going to Suzhou tomorrow, will you come with us?
B:算我一个。
Suàn wǒ yíɡe.
Count me in!