Generally, any antidepressant or antianxiety medication, especially one prescribed and taken every day. "Crazy pills" is a light-hearted, self-deprecating way of talking about these medications with close friends, trusted
acquaintances, etc., without bringing the associated (and
unnecessary) social stigma along for the ride. If used in
conversation with a person you do not know, the intended meaning may be lost.
Common examples: Zoloft (sertraline), Lexapro, Wellbutrin.