He's very simple-minded even though he's very good at kung fu.
6 seconds sound clip from the Mysterious Footworks of Kung Fu movie soundboard.
You can hear this line at 00:50:39.297 in the Blu-ray version of the movie.
Quote context
[...]
- But the masked man's bound to attack again. We can't lose any more.
- We must stop him, but he is too quick. His kung fu's too good. And our best fighters are away.
- We can't just sit still and watch the next lot get robbed.
- Have you heard of any new fighters in town? Maybe we'll use them, we've gotta do something.
- One is a worker, he's down at the docks at the moment. Three-Eyes Liu.
- He's very simple-minded even though he's very good at kung fu.
- So you must be Leng Ching-Shan.
- Mister, Mr. Leng Ching-Shan, my name's Chu. I work for Mr. Shu.
[...]