Ok, I know this isn't a scholarly article. There have been heroic attempts to classify and describe the vast array of instruments that exist and have existed throughout the world, but this isn't one of them.
Important factors in describing instruments include: method of sound production, materials used in construction, tuning practices, cultural factors that influence the design and use of an instrument, political conflicts which influence the spread or decline of particular instruments, linguistic or etymological factors that influence the naming of instruments, etc.
If you present this type of information to a group of children (or even most adults), you are likely to receive a lot of yawns and blank stares. If, however, you just mention the word sackbut, you are almost guaranteed a response of smiles and giggles.
The scholarly among us may point out that funny instrument names were usually not meant to be funny at the time the instrument was commonly used. The fact that we now find them humorous is a sad commentary on the current disassociation of modern society with historical cultures.
It might be worth discussing this in greater detail, but not now. For now, I will content myself to just list some instruments that sound funny to me. Click on the name if you want to learn more.
Sackbut, serpent, crumhorn, racket, hurdy-gurdy, didgeridoo, diddley bow, bombard,
sarrusophone, clavicytherium, banjolele, crotalum, oliphant, heckelphone, kazoo, theorbo, trautonium, ophicleide, orpharion, viola pomposa, nose flute, nose whistle
What instrument names sound funny to you? Which instrument do you think has the funniest name? So far, my vote goes to sackbut, but I would be happy to change my mind if you come up with something better.
If you would prefer a more serious discussion of this topic, please see Of Phonemes, Fossils and Webs of Meaning:
The Interpretation of Language Variation and