A name given to people usually spinning in circles with their arms spread out swaying back and forth in rhythm to the beat. Could once be found attending Woodstock and any Grateful Dead concert with a head full of acid.
I imagine the feeling of doing this would be unbelievable amazing and euphoric, or nauseating and there wouldn't be any sensation worse. Twirlers moved and would flow gracefully as if they were an extension of the music, but could reek of b.o. from following the band for months at a time in a VW bus only to bathe in a river when time and weather permitted.
These twirlers would spin until they fell over, even twirling non-stop between songs. They would only twirl in open areas, this was so they could twirl without being interrupted. Making it through a field of twirlers without being hit was a challenge most people wouldn't want to take, but for some they attempted their hand at fate and would go head on against the flailing appendages of the twirlers.
This is also a popular term for the people that spin batons
and pizza dough