I saw this girl walking the other day and took a picture of the back of her hair because it looked so cool. Sorry girl if this is your head and I did not ask you but you were walking so fast! Her hair looked as if she had literally dipped it in pink. She had a napoleonic thing going on (with the brown to blonde to pink) I think you could do this in two DIYs:
1) Semi-Permanent: Tie your hair into a low pony-tail then slide the hair tie down to how much of the dye you want on your hair. Then put the pink dye on this part of your hair for the indicated amount of time on the bottle.
2) Temporary: Select what piece of your hair that you want to “dye” and then spray Temporary Hair color spray that you can get from somewhere like walgreens . The best part is that it washes out so you don’t have to commit, or you can try it before you commit.