You know what it is? He's killing bugs with Kung Fu.
5 seconds sound clip from the Disciple of Shaolin Master movie soundboard.
You can hear this line at 00:38:41 in the DVD version of the movie.
Quote context
[...]
- Oh it's itchy, oh I'm itchy!
- So, I've got you you damn little bedbug. So you'd have a go at me, would ya? That'll fix ya.
- Uncle? Uncle? Uncle, it's already late,
- What's with the beggar? What's he up to now?
- You know what it is? He's killing bugs with Kung Fu.
- Hey, what's the big joke? Don't you know how late it is? You two should be asleep.
- My god? Has he gone to Chin Lian mountain alone?
- That young man's too tough for his own good.
[...]