Well, one of them is solid, the other's hollow. It's the teacher's trick.
4 seconds sound clip from the Kung Fu Master Named Drunk Cat movie soundboard.
You can hear this line at 00:32:19.400 in the DVD version of the movie.
Quote context
[...]
- Yeah.
- Hello.
- Hi.
- What is this? Why are you in there?
- Well, one of them is solid, the other's hollow. It's the teacher's trick.
- Haven't paid my fees in three months.
- Teacher.
- My friend wants to learn kung-fu.
[...]