翻(fān)脸(liǎn)

Fān liǎn
翻 脸

Means:Not be friendly any more.

For example:

Wèi le qián,tā hé péngyǒu fānliǎnle.
为 了 钱, 他 和 朋 友 翻 脸 了

(He abandoned his friends for money.)