"draw dun from the mire"
Proverb
Act 1,
Scene 4
Lines 38-41
Mercutio
The word “dun” when used as a noun refers to a brown horse, and that’s how it's used in the proverbial expression that Mercutio is referencing, “to draw dun from the mire.” Mercutio says that if Romeo is a dun, then they’ll pull him out from where he’s stuck; but it’s not mud in which Romeo’s stuck, but love — up to his ears.