I've deliberately made it a bit small without a link to a larger version for a reason. This is how I first viewed the comic through my RSS reader and I sat there for a minute thinking, "OK, I'm sure there's a joke there, but I'm just not getting it."
My feed for Knight's comics displays them in my reader well-enough, though at a smaller size than I think he intends. So for some of his comics -- generally, the ones with a lot of text -- I have to click through to his site to see a version that's enlarged enough that I can read it.But here, the text was quite legible at the reduced size as was the basic structure of the comic. But what was obscured was the detail which makes the joke work.
Here's a larger, clickable version...
But the gag only works if you can actually see the hair pick well enough to tell what it is. It's already out of context (by virtue of being up the child's nose) so it needs to be made particularly clear to the reader what it is.
So the moral of the story: make sure that critical points of your story/cartoon/gag are readily identifiable BY YOUR AUDIENCE. A joke can look great at the poster board size you may have drawn it at, but if it loses legibility as it reduces, then you might need to rework your piece a bit.