HOW TO REMOVE GREEN GOO FROM YOUR HORN.
The first thing to understand is why green goo collects in your horn. Green goo originates in the detritus left over from cracked or split notes. Although much of the acoustical debris from these notes is expelled from the bell, to annoy listeners, the non-acoustical residue remains inside.
As these broken notes accumulate, they are attacked by a species of yeast that grows only inside horns. In the dark, moist environment of your horn's innards, the yeast causes these notes to suppurate and turn green. Hence green goo. It is referred to in the literature as corneous catarrh.
The green goo collects in low places and nodes. If enough accumulates, the valves slow and the tone gets stuffed up. The pitch gets dull and listless. Ennui and malaise spread.
The simplest and most obvious cure is not to miss notes. This is the course I have chosen. However, my astounding success has caused students to flock from miles around, and, of course, they expect my guidance on banishing green goo from their horns.
If you are not in my fortunate position, let me recommend that you remove green goo from your horn the same way you would remove other nasty, green fluids that gather in your node. Put a large handkerchief over your right hand, and put it in the bell, not too far. Then blow briskly through the mouthpiece. Be careful not to seal the bell too tightly, lest your instrument suffer a painful swelling of the first branch, referred to as a hornia.
You might also use one of the superb medical products designed to alleviate this condition. I recommend Dristan. As Hans Pizka will tell you, after five hours of Dristan, you won't have worry about green goo any more.
Gotta goo,
Dr. Cabbage