Originally Posted by Sweetone
I doubt you know me well enough to guess. The only reason I haven't responded sooner is I'm trying to think of some.
Let's see - It would probably take a combination of things to really get me nervous.
A passenger putting something in the galley or lavatory - of course depends on what it is.
An individual or several people trying to distract or block a FA.
A glimpse of some type of prohibited weapon - a real one, not the bogus liquid type.
Sudden changes in behavior - such as a group seen together in other areas of airport who suddenly act as complete strangers
Adults who pay too much attention to children traveling alone. (I'm a mom)
These are some examples of behaviour I would continue to observe. Of course they could all have a logical explanation, just something to keep an eye on.
Ned69 - You gave me a good laugh.

Your list sounds reasonable on paper (and I realize you were kind of put on the spot for it so I won't tear it apart). However, like all lists there is an awful lot that can be left to individual interpretation and there is much room for abuse. As a victim of such abuse, I don't like the idea of putting such power in the hands of other passengers. I'm on the plane to get somewhere, not to be voted off the bloody thing.