Clarification: Handholding Rollerbladers Wearing Earphones Are the Devil
The kind without headphones are merely lesser dark angels of some sort.
(Just got back from a bike ride on the Lake Shore bike trail thing again.)
Also: groups of people doing tai chi look cool and synchronized and zen. Individual people doing tai chi look crazy (until you put them into context), or at least, they look like people communicating with semaphores, minus the flags.