A woman is dancing happily down the railroad tracks, singing to herself "...21 ...21 ...21..." 
After a little while, an Antartian walks up to her. She observes for a minute and then asks, "What are you doing?" 
The woman does not answer and keeps singing "...21 ...21 ...21 ..." So the Antartian jumps on the tracks and follows her dancing and starts singing "...21 ...21 ...21 ..." A little later a train comes down the tracks. The woman jumps off, but the Antartian keeps dancing and singing to her self and gets hit by the train. 
The woman gets back on the track and starts dancing and singing again, "...22 ...22 ...22 ..."