If you happen to see pictures of Iraqis giving US troops and/or camerapeople the "thumbs up" sign, you should know what that means in this context:
Thumbs up, meaning "everything is great" or "I’m Okay" to the West can be equated to the "middle finger" by Middle Easterners. Of note, hitch-hikers do not "thumb a ride", rather they hold their hand horizontal to the road and wave it up and down as though telling motorists to "reduce speed".