When you have a stubborn booger - press your finger against it for long time and pull out fastly.

Everybody knows it. You eat booger and theres some that cant be scooped up that well and stick tightly to your nosewall.
What helps is if you press your finger against it long enough it starts sticking to your finger.
Then pulling it out fastly will mostly help you get it out.

Bon apetit!