I too carry a ziploc bag in case I get sick. It started when I had horrible "morning" sickness (that was never in the morning
) but continued after pregnancy. It just makes me feel more comfortable that I have a backup.
I think vomiting into a bag is greatly preferable to any other option.
Now poop is a totally different story. I can't figure out how you could go in a bag without inappropriately exposing yourself in public. In that unlikely and highly unfortunate situation I think the best/only option would be to go in your pants.
Honestly if someone pulled their pants down to poop on the monorail, I'd be making sure security was contacted once we were off to deal with the situation.

I think vomiting into a bag is greatly preferable to any other option.
Now poop is a totally different story. I can't figure out how you could go in a bag without inappropriately exposing yourself in public. In that unlikely and highly unfortunate situation I think the best/only option would be to go in your pants.
Honestly if someone pulled their pants down to poop on the monorail, I'd be making sure security was contacted once we were off to deal with the situation.