@kickycan,
I have the answer, I am 16, and I get that all the time.
What I do is I go to a mirror, shine a light down my throat, and when I see a yellow spot poking out, I push the area around it (use only 1 finger), almost like a pimple, but instead of pushing the surface together, I go right next to the booger, then I push into the wall of my throat, then shift my finger into the booger while still pushed in. This method should squeeze that little bitch right out, and now you're throat-booger free for a week until that ******* thing starts to form again.