The White Stripes called: they want their shirts back.
Tegan and Sara's Sainthood and El Perro Del Mar's Love is Not Pop CDs came out last week, and they both feature the same jailhouse-style striped shirts on their covers.
Here's an explanation, courtesy of Cosmos Magazine (not to be confused with Cosmo Magazine). According to the article, wearing horizontal stripes - especially black stripes - adds more height to the subject and appears more slimming than wearing vertical stripes:
"Peter Thompson found that if two identical squares are drawn side-by-side, one with horizontal stripes, the other with vertical stripes, then the square with the horizontal stripes looked taller and narrower than the other with vertical stripes.Which explains why referees, prisoners, and the American flag, all look so natty, healthy, and svelte.
"I found that this relates to clothing too," said Thompson. "In HelmHoltz's Handbook of Physiological Optics he noted that ladies' frocks with cross stripes on them make the figure look taller."