The thought of that is... terrifying. They endangered you and everyone else around them by doing that bullshit.
I've been a designated driver for my family once before, and I'm happy I was doing so at that time, because it beats the alternative of being scared that you'll **die** because the driver is drunk, or dying, or surviving while someone else dies.
It's irresponsible as hell to not have at _*least_* one designated driver, regardless of context.