From the Miller's Tale of Chaucer's Canterbury Tales showing the difference between Middle and Modern English

Caution: Chaucer was sometimes a little coarse; lewd and risqué. Note how some "vulgar" words have not changed since the Middle Ages.

3798 This Nicholas was risen for to pisse, This Nicholas was risen to piss,3799 And thoughte he wolde amenden al the jape; And thought he would make the joke even better;3800 He sholde kisse his ers er that he scape. He should kiss his ass before he escapes.3801 And up the wyndowe dide he hastily, And he opened up the window hastily,3802 And out his ers he putteth pryvely And he puts out his ass stealthily3803 Over the buttok, to the haunche-bon; Over the buttock, to the thigh;3804 And therwith spak this clerk, this Absolon, And then spoke this clerk, this Absolon,3805 "Spek, sweete bryd, I noot nat where thou art." "Speak, sweet bird, I know not where thou art."3806 This Nicholas anon leet fle a fart This Nicholas immediately let fly a fart3807 As greet as it had been a thonder-dent, As great as if it had been a thunder-bolt,3808 That with the strook he was almoost yblent; So that with the stroke he was almost blinded;3809 And he was redy with his iren hoot, And he was ready with his hot iron,3810 And Nicholas amydde the ers he smoot. And he smote Nicholas in the middle of the ass.3811 Of gooth the skyn an hande-brede aboute, Off goes the skin a hand's breadth about,3812 The hoote kultour brende so his toute, The hot plough blade so burned his rump3813 And for the smert he wende for to dye. And for the pain he thought he would die.3814 As he were wood, for wo he gan to crye, As if he were crazy, for woe he began to cry,3815 "Help! Water! Water! Help, for Goddes herte!" "Help! Water! Water! Help, for God's heart!".