跑野馬

Simplified: 跑野马

pǎoyěmǎ ㄆㄠˇ ㄧㄝˇ ㄇㄚˇ

    • to let one's thoughts wander
    • to talk off the point

Character by character

Saying俗语俗語

Idiom惯用语 · Widely known

Literally
to run wild horses
Meaning
To let one's thoughts wander without restraint, or to talk off the point. Mildly humorous.

Sources