- Oh, yeah? Who says?
- Says who?
- Why?

5 seconds sound clip from the Space Jam movie soundboard.

You can hear this line at 00:19:22 in the Blu-ray version of the movie.

Quote context

[...]

- Oh, fear clutches my breast.

- We ain't going nowheres.

- Eh, not so fast, doc.

- You just can't turn us into slaves. That would be bad.

- You've gotta give us a chance to defend ourselves.

- Oh, yeah? Who says?

- Says who?

- Why?

- Just a sec. There. Read them and weep.

- What's this?

- Give them a chance to defend themselves.

- Aw. Do we have to?

[...]