US beer drinkers might think that odd, but only until they learn the meaning. Not surprising, the grateful response usually results in a flurry of orders for stout. First brewed in the 1700's, the stout you drink has disputed origins.
Some writers describe it as the son of porter.
Others insist stout existed long before. In historical beer lexicon the word 'stout' did precede porter, and it was used with regularity. Hey there squire, welcome. They could have used words like strong, full, big or impressive, but in their vernacular they described extra strength beers as stout. Here again the word stout was used as an adjective when, for lack of a better name, they referred to the new, fuller tasting variation as a porter-stout.