When one tries to do actions on touchscreen immediately after picking their nose. The booger remnants on the finger cause the finger to stick to the surface of the touchscreen.
I was about to get a top score on my tablet when I picked my nose and forgot to properly clean off my finger...booger finger.
a person at a club or bar who is asked by a bouncer or management to leave and refuses (much like a booger stuck to a finger won't get off).
"Sir, I'm going to have to ask you to leave."
"Man, what a booger finger..."