if they are muslim they are probably guilty of something. I say carry around a photo of Bush or ariel sharon in your pocket and if you see someone who looks arab show them the pic, if they recoil they are probably a terrorist (sorta like vampires and crosses)
The ONLY word of Arabic I know, I learned from a former fellow carpooler whose husband is Moroccan (and a farther-right Republican than I am) - it is "ZUB". It means "penis". You can imagine the fun I and the other woman in the carpool had on that drive home. "Zub a dub dub, three men in a tub" and so forth. But we did have a plan - if we heard a couple of guys speaking a language we didn't recognize, we'd say "Excuse me, your zub is showing" and see if they looked.
Her husband was actually quite upset that she told us that word - unladylike.