I guess if I had to do something like that, I might write a very simple program that asks a few questions and then "magically" tells the user their age or birthday or some number they've thought of, etc. (Based on some simple algebraic identity...probably you've seen many such.) That might catch their attention, and then you could show them the few lines of code. Since Perl code can be written so that it is almost English, that should be understandable and also illustrates things that programs can do - communicate with user, store input in a variable, do arithmetic calculations, etc. In fact, it's sounding more doable all the time ... (except maybe for the "who don't/barely speak english" part.) Even if they don't understand perfectly, they'll come away with some ideas, and that's probably the best you can do in the situation you describe.
Good luck!
chas