Creating custom flags and flag effects for clothes

I have just been messing about with some of the json files and was wondering how do I create a custom flag and effect to apply to an item.

For example say I made a pair of stilts, and wanted to add a flag that makes the character occasionally stumble.
How would I create the flag to apply to the item?

If i’m not mistaken, that would require a BIT of coding, which i don’t know how to make.

Ah, I was worried it might. :frowning:

You will need some coding, and would look in iuse.cpp and iuse.h if I am not mistaken.