You know those whistles that are popular at kids birthday parties, that unroll a paper tube and make a really annoying noise? Well, my daughter ripped off the paper tube and started blowing it.
It's a very annoying timbre. The structure of it seems to explain why it's annoying. There is the usual fundamental and 5th harmonics. But there is a whole host of others, some of which are exactly opposite each other. Opposite, means that they are a tritone relationship (possibly with octave differences).
Whatever, the reason. It's annoying and quite spiky.