In Elizabethan England, the word "nim" was slang for "to steal." That's perfect because this guy is a member of Falstaff's thieving, trash-talking posse—but not for long. After Nim and Pistol refuse to deliver Falstaff's love letters to the "merry wives," they have a falling out with Falstaff and end up snitching him out to the husbands of Mistress Page and Mistress Ford.
Oh, did we mention that Nim and Bardolph are both hanged for stealing in the play Henry V? Like Bardolph and Pistol, Nim's character isn't developed much in Merry Wives. Mostly, Nim runs around the play acting rowdy, talking smack, and sneaking the word "humour" into as many sentences as possible.
Brain Snack: In this play, "humour" isn't defined as something hilarious that makes us laugh. The Elizabethans thought the human body was made up of four different types of "humours" that shaped a person's health and personality: blood, phlegm, yellow bile, and black bile. People thought that if a person's humours were out of whack and unbalanced, they weren't healthy.
Why does Nim use the word "humour" so much? Our guess is that he wants to sound smart but he just winds up sounding ridiculous.