Choir boys do it unaccompanied. Clock Makers do it mechanically Clowns do it for laughs. Clu programmers do it in clusters. Cluster analysts do it in groups. Coaches whistle while they work.
Cocktail waitresses serve highballs.
Collectors do it in sets. Combinatorialists do it a countable number of times, sadly. Combinatorialists do it discreetly. Comedians do it for laughs. Communists do it without class Computer Game Players just can't stop.