Brake Fluid in a transmission?

[69GMC396]

I was going to work the other day in my 1994 2500 6.5L and I passed someone and when it kicked down the tranny slipped. It really makes me mad considering the transmission is only 2,000 miles old. This guy at work. (When I tell you the next part people are going to say is he on crack? He is. Literally.) He told me to put a little brake fluid in the tranny to make it stop slipping. He said mainly all tranny oil is is brake fluid and oil. I didn't take his advice. But I wanted to know is that true that it will stop slipping or would it just fry the tranny.