The 1.25 inch Iron Man "Eat My Repulsor" Button is based on Marvel's number 1 shellhead, Tony Stark! Wait, who else could we call shellhead? Suppose Juggernaut meets that requirement. Maybe Magneto too. What about Thor, if he has that giant winged helmet on? Okay, okay...maybe quite a few of them could be shellhead. Still, Iron Man is the number 1...mainly because nobody else can tell him other wise.