He flies in as a superhero, only to be taken hostage. On Earth, he is the most powerful superhero, with one horrible weakness. Aluminium, which happens to be the most common material in the earth's crust. So, terrorists constantly threaten to destroy him and take away Earth's only protector.
Powerful Man flies in.
Powerful: I have come to save everyone in this building, and arrest you terrorists.
Terrorist: I've got an aluminium can.
Powerful: Again? How do you people know about my weakness?
Terrorist: The adverts on telly.
Cuts to the adverts.
Man: Are you tired of being captured by Powerful Man?
Man: Do you wish you could just strip him of his powers?
Villain: Sure do.
Man: Well now you can, with Aluminium!
Villain: Wow, Kevin, that's great! And are you sure Aluminium, really works?
Man: Yes I am and if you're not satisfied you can always write to us.
Villain: But if it doesn't work, won't Powerful Man just have killed me?
Voicover: Aluminium! It really works. Paid for by Aluminium Mining corp.
Powerful: I really hope they run out of money.
He is hit on the head by an aluminium bar.
I can really see this character taking off. Not only does it showcase my own fear of aluminum, it lets everyone know about the dangers of advertisement.