In Romeo and Juliet, when Sampson says he will not "carry coals" (Act 1, Scene 1), what does he mean? What literary technique is being used in this...

“To carry coals” is an old English idiom meaning to be insulted, or to be the butt of jokes.  This stems from the status of coal carriers – or colliers, as Gregory makes mention of in the next line – in society.   It was a dirty and undesirable job, and so was deemed unfit for the better members of society.  For this reason colliers were looked down upon and often insulted, and hence the...

“To carry coals” is an old English idiom meaning to be insulted, or to be the butt of jokes.  This stems from the status of coal carriers – or colliers, as Gregory makes mention of in the next line – in society.   It was a dirty and undesirable job, and so was deemed unfit for the better members of society.  For this reason colliers were looked down upon and often insulted, and hence the phrase.  So, when Samson says “Gregory, o’ my word, we’ll not carry coals,” he means that they will not stand to be treated like the basest members of society, i.e. insulted.  We can assume from this that from the very beginning the Capulets were roaming the streets gunning for a fight with the Montagues. 

The silly turns of phrase that Samson and Gregory bandy with relation to coal are good examples of puns, a type of wordplay that Shakespeare utilizes to great effect in his plays.  Here, Samson is using “to carry coals” in a figurative sense, and yet Gregory responds with the literal meaning of the phrase – if they were to carry coals, well then they would be colliers.  Samson then spins off the word collier, stating that “I mean, an we be in choler, we’ll draw.”  Here he plays off the similarity between the words collier and choler.  And Gregory then makes good use of the fact that choler and collar are homophones, and uses again Samson’s word draw when he says “Ay, while you live, draw your neck out o’ the collar.” 

The irony here of course is that Gregory offhandedly insults Samson throughout their entire exchange, even though the latter swore at the beginning that he would not tolerate it.  This further goes to show that their beef is purely with the Montagues; or at the very least that Samson is not very bright.