It represents a sort of nut, itself too bulky for a railway truck.
You miserable little beast—with cats everywhere, and not a nut for miles!
He'll be out for de goods; it's a gal owns him, an' dere'll be nut'in' doin'.
"Smash him, Sam—smash in his nut for him," piped the smallest Micky cheerfully.
You cracked the nut with me; it doesn't become you to sneer at it now!