Definition of "booger"

Mama says you mustn't pick boogers out of your nose with your fingers; you must use your handkerchief.

1948, Publication of the American Dialect Society, page 16

Now in the halls of the necro lord / Flash of fear when he sees my sword / Raped his woman, smoked his bone / Leave a booger underneath his throne!

2006, Strapping Young Lad, “Far Beyond Metal”, in The New Black

The latter is discovered by Caesar, Maurice, and their compadres living in a crumbling, snow-packed ski lodge, its antler chandeliers hung with boogers of ice in a mockery of humanity’s pretensions of alpha-predator-hood.

2017 July 7, Ignatiy Vishnevetskyg, “The ambitious War For The Planet Of The Apes ends up surrendering to formula”, in The Onion AV Club‎