信口胡说

信口胡說
xìnkǒuhúshuō
to speak without thinking; to blurt sth out

CEDICT

不加思索的随意乱说。

重編國語辭典

Entry Composition

1 信口 xìnkǒu
  1. to blurt sth out
  2. to open one's mouth without thinking
2 胡说 húshuō
  1. to talk nonsense
  2. drivel