Near knuckle

[FredPuli]

'Near the knuckle' nowadays means that a joke is 'off colour', vulgar or has some sexual content or allusion, . What's the origin of this expression /

[Quizmonster]

'Knuckle' has been used to mean 'a limit' of some sort since the 16th century. There were such references as being 'up to the knuckle' in blood and 'pledged up to the knuckles'. 'Near the knuckle', which first appeared in the 1890s, seems to be just an extension of that idea.

[Headtime]

Could it also be a butchery reference, i.e slicing a leg or joint 'near the knuckle' i.e very close?

[Plado]

On another web search I found a much more plausible origin of this phrase. When carving meat you can get near to the knuckle or bone and be unable to cut any deeper, so this could mean a remark that is near the knuckle is close to the limit (of good taste). It said that 'near the bone' has the same meaning. It just sounded more logical to be the origin. I did wonder if it had some origin in Boxing as in 'below the belt' which can also refer to a remark that is sneaky, cheating or unkind in some way likely to cause offense.