In case you don't know the reference to the post title, the
slogan for a brand of candy called Skittles is "Taste the Rainbow" and
Park Si Hwan's album name is called "Rainbow Taste".
I have his "Rainbow Taste" album and while flipping through it recognized one of the shirts he is wearing. Park Si Hwan is wearing the T BALL PLAYER PATCH DOG T SHIRT (2015 VER) in green from a Korean brand that personifies animals in their designs called Beyond Closet. Buy here.
