Probably, you’ve seen fans in ballparks whacking together those long plastic sausages. Newspaper articles say the Thunder Sticks are really loud. They look like plastic balloons, which you wouldn’t think would be loud. Is there something inside?
Aha! I was able to attend a couple of the Timberwolves playoff games, at which they honored me and my sister (and about 20,000 others) with these ThunderSticks.
They come to you deflated, and yes, they are rather like blown up sausages when you get the air in there. However, they’re not made of rubber, but rather of mylar. Because it’s metallic, it puts out quite a bit of sound indeed, especially if you blow them up as much as possible. The mylar also has a bit of echo to it as well, to add to the sound.
They are surprisingly loud - before I saw one, I also wondered how they were noisy. Mylar!
Snicks
According to this FAQ :
“Tarzan hear noise. White man kill with thunder stick!”
That was my first reaction.
Carry on.
Thank you. By the way, LDPE is usually an abbreviation for low density polyethylene. 
The very idea of these johnny come latelies appropriating a nickname of long standing for a whipper snapper toy sound. They are nothing like the REAL THING-
A WINCHESTER 30.06
So let it be!
I saw a short featurette on the inventor of this wondrous item, an American multi-millionaire (where else but America can you get rich inventing balloons to bang together?). He was being interviewed in the stands at a baseball or basketball game. I don’t know for sure that they all are made of mylar, which I believe is comparatively expensive. But they are ingeniously self-sealing when inflated, virtually leakproof, and they do make a terrific loud din when you smack them together, because of the large volume of air being rapidly compressed and then allowed to reverberate against the plastic skin stretched tight as a drum (literally) around it. We enjoyed a tremendously fun experience with them down here recently in Tampa Bay, Florida while rooting for the Lightning, the top team in the world of ice hockey. Go figure. This came delightfully at the expense of the Canadian purists who maintain the championship trophy “belongs” to Canada and who plaintively deride the air-filled toys as crutches for “non-hockey fans” to make a suitable sound level in the arena while our team (comprised of over 70% Canadians) was busy winning the Stanley Cup. The Lightning and Thunder Stix–they go together.
30.06. hell! What about the 44.40?
Or the 45-70 for that matter!