To make a wholehearted, unconditional commitment (to some group, or idea, or plan) in contrast to choosing an
alternative. It emphasizes a resolute decision (good or bad) in response to a choice.
This is a reference to the "
electric Kool-Aid acid tests," which were LSD parties held in the
San Francisco Bay area in the mid 1960's. Someone who was willing to drink the LSD-laced Kool-Aid had, symbolically, made a choice to join (if only for a few hours) a counterculture that stood against conventional society. Once you take acid, you're committed -- the trip lasts for hours and you can't cut it short or change your mind. Once you've drunk the kool-aid, you're firmly committed.
IMHO it is not about suicide: kool-aid isn't a symbol for poison.
Coach got his players to drink the kool-aid.
I really like
Macintosh computers; I've totally drunk the Apple kool-aid.
That berserk guy who tried to kill people at the Tides
Foundation really had drunk the kool-aid that the right-wing media were serving.