Isabel... you got me with that question ... so. I looked it up
"A rainstick is a long, hollow tube partially filled with small pebbles or beans that has small pins or thorns arranged helically on its inside surface. When the stick is upended, the pebbles fall to the other end of the tube, making a sound reminiscent of rain falling.
The rainstick is believed to have been invented by the Aztecs and was played in the belief it could bring about rainstorms. "
So, this stall holder was not just advocating a 'Buddha for Christmas', but offering the opportunity to magic up rainstorms, which I suppose means Snow if you live far enough north.
He must have sold a lot over the last few months ....... Blizzards & Snow in USA and atrocious floods in UK.
If I see him next Christmas I'm gonna have a serious word with him about it all!