Okay so I'll be a terrorist and make 100 devices the size of a lunch box. 1 in 10 of them in full of C4, but they are entirely identical otherwise. I paint all of them with Spiderman 3 logos on them. I'll put a couple of the duds which will be full of candy and movie tickets in really obvious places for people to find and make news about. I'll leave the armed ones in near schools and children's hospitals. Since the first ones that were found were full of presents, those little kiddies will climb all over themselves to be the first to open the ones full of C4. Wee!