And the plural is...

One Englishman, a bore; two Englishmen, a club; three Englishmen, an empire.

One Irishman, a drinker; two Irishmen, a fight; three Irishmen, a partition.

One Frenchman, a lover; two Frenchmen, an affair; three Frenchmen, a ménage.

One German, a burgher, two Germans, a beer-parlour; three Germans, an army.

One American, a businessman; two Americans, a market; three Americans, a cartel.

One Italian, a tenor; two Italians, a duet; three Italians, an opera.

One Russian, an anarchist; two Russians, a chess game; three Russians, a revolution.

One Japanese, a gardener; two Japanese, a cult; three Japanese, electronics.

- from Eats, Shites & Leaves by A. Parody