Dr. Egon Spengler: There's something very important I forgot to tell you.

Dr. Peter Venkman: What?

Dr. Egon Spengler: Don't cross the streams.

Dr. Peter Venkman: Why?

Dr. Egon Spengler: It would be bad.

Dr. Peter Venkman: I'm fuzzy on the whole good/bad thing. What do you mean, "bad"?

Dr. Egon Spengler: Try to imagine all life as you know it stopping instantaneously and every molecule in your body exploding at the speed of light.

Dr Ray Stantz: Total protonic reversal.

Dr. Peter Venkman: Right. That's bad. Okay. All right. Important safety tip. Thanks, Egon.