The biggest taboo in friendship is saying one thing and meaning another.
Tips
history
Cited from Feng Menglong's Ming-dynasty story collection 《醒世恒言》 (Xǐngshì Héngyán, 'Stories to Awaken the World'), which scolds a character: 'You said all that last night, yet 口不应心 — you did this thing!'
memory
Read it literally: 口 (mouth) 不 (does not) 应 (correspond to) 心 (heart). What comes out of the mouth doesn't answer to what's in the heart.
