To put it plainly, it appears people need to know the answer to one question. Will this burger turn your potty pebbles a terrifying shade of red? On March 31, when the burger is released, the mystery may finally be solved. Look at that thing! How could it not do something crazy to our bodily fluids? Why the heck is the bun red, you might wonder? According to their YouTube video campaign, BK says hot sauce is baked right. Into. The. Bun.
Some are saying, it will turn your poop bright red. Enjoy.

Source: http://www.eonline.com/news/752420/...-worried-about-a-certain-colorful-side-effect
Source: http://www.bk.com/menu-item/angriest-whopper-sandwich