From This is True:
It is now illegal in Colorado to wear aluminum underwear.
“This is serious business,” insists State Sen. Stephanie Takis, who sponsored the bill. “We have laws against using crowbars as theft devices, but if you were lining your underwear with aluminum foil, that was not a crime.”
It is now.
Apparently, shoplifters found such so-called “iron pants” allow them to sneak stolen items past anti-theft scanners at store doors. The law also allows store security officers to detain people who “crackle when they walk,” but provides an exception for aluminum britches worn for “personal amusement.” (Colorado Springs Gazette)
… Which is probably covered under vice statutes.