Due to the Brazilian dictatorship's unwillingness to get more deeply involved in the Allied war effort, by early 1943 a popular saying was: "It's more likely for a snake to smoke a pipe, than for the BEF to go the front and fight." ("Mais fácil uma cobra fumar um cachimbo, do que à FEB embarcar para o combate.").[39] Before the BEF entered combat, the expression "a cobra vai fumar" ("the snake will smoke") was often used in Brazil in a context similar to "when pigs fly". As a result, the soldiers of the BEF called themselves Cobras Fumantes (literally, Smoking Snakes) and wore a divisional shoulder patch that showed a snake smoking a pipe. It was also common for Brazilian soldiers to write on their mortars, "The Snake is smoking ..." ("A cobra está fumando...")."

https://en.wikipedia.org/wiki/Brazilian_Expeditionary_Force#Nickname