Warning: this one may be a bit gross...
My son, who is almost three, fairly regularly gets large clots of dried mucus wedged deep up his nose.
They can stay there for days without coming out on their own, and they cause a noticeable whistle when he breathes.
The rubber suction bulb our hospital gave us when he was a newborn does absolutely nothing to help; the masses are too far up, and too big. Not to mention my son hates to have them shoved up his nose!
He can still breath with them, and they only really seem to cause him discomfort when they've been there long enough to have hardened (at which point they'll typically come out on their own after a few more days, usually with a big sneeze).
There is a medical reason why my sons... boogers... may be a bit bigger and thicker than average, but we've seen a specialist, and he agrees that they're not symptomatic of any actual medical problem.
So the question is: what, if anything, do we do about this? Do we try to extract them for him? We've tried teaching him how to blow his nose, but he just doesn't seem to be getting the idea.