JUSTIN BIEBER has made some bizarre fashion choices over the past few days.

On Tuesday in London, he wore ugly, saggy pants and a yellow baseball cap with SPIKES all over it. But he later said he did it on a DARE...because a friend said he didn't think Justin would do it.

Yesterday, while still in the U.K., Justin was spotted SHIRTLESS...with jeans that were so low, they were entirely below his butt. He WAS wearing underwear, at least.

RELATED COMEDY: Justin Bieber and Ke$ha both celebrate their birthdays today. So today's horoscope definitely does NOT say, "You will make music that will stand the test of time."