Oh man... you mean those little plastic monster things right? That's a blast from the past...
Those were so popular when I was in like... fourth grade I think it was. Long time ago in elementary school. My classmates would play with them all the time during recess and stuff, but I never had any because my mother refused to allow me to participate in any kind of "fads" whatsoever. Someone in my class was nice enough to give me two or three of theirs, and then my dog ended up eating them shortly afterward. I was pretty upset.