don't drink the kool-aid
Comes from a religious mass suicide from poisoned kool-aid. When people are going to a meeting of a controversial group, they are sometimes warned not to drink the kool-aid
Oh, you're becoming a scientologist? That's ok, just don't drink the kool-aid.
don't drink the kool-aid
One specific form of the more general term drink the kool-aid. Please refer to that definition for a more complete understanding.
"Don't drink the Kool-Aid"