- Who would believe you?
- You must believe me.

4 seconds sound clip from the 13 Style Strike movie soundboard.

You can hear this line at 00:40:04.700 in the DVD version of the movie.

Quote context

[...]

- That is the Swallow Strike. Come again.

- That is the Swallow Style. All right, now you practice it hard. I'm going to lie down.

- You monkey!

- You can't do anything to us now.

- That's right. You aren't good at Kung Fu like that.

- Look here, sisters, that's right, I won't do it again.

- Who would believe you?

- You must believe me.

- All right, how about this? Why don't we have a fight now? If either of you can hit me, I'll admit defeat. You agree?

- Oh. What are we going to do?

- Oh, it's up to you. But if you can't hit me, I'll admit defeat. What do you say?

- All right!

- Are you all right, girls?

- What kind of Kung Fu is that?

- Oh, it's called the Strong Arm.

- Oh, the Strong Arm? You see, the Strong Arm it's unbeatable. I took four policemen at once. They weren't any match for me at all with this.

[...]