You've been the Guinea pig long enough.
4 seconds sound clip from the The Nutty Professor (1996) movie soundboard.
You can hear this line at 00:34:21 in the Blu-ray version of the movie.
Quote context
[...]
- Sherman! I brought you some nice fried chicken, Sherman.
- Oh, my god! He's gonna blow!
- Way to go, son! That's my boy!
- No!
- You've been the Guinea pig long enough.
- It's time to see if this stuff really works.
- I'm thin! I'm thin! Look at my cheekbones! I have cheekbones! Look at my cheekbones! Yes!
- Oh, god, I'm thin! I'm thin! I'm thin! I'm thin, I'm thin.
[...]