心猿意马

1. • lit. heart like a frisky monkey, mind like a cantering horse (idiom) fig. capricious (derog.)
2. • to have ants in one's pants
3. • hyperactive
4. • adventurous and uncontrollable

Character by character

• 心(xīn)heart
• 猿(yuán)ape
• 意(yì)idea
• 马(mǎ)surname Ma