" i'm wore slap out"

A freind of ours recently used the phrase
" i'm wore slap out" refering to her long work week, does anyone know where this phrase came from, she said she had heard her mother say it for years.

I worked with someone a while ago who was from the Southern or Western part of the US and he used to use that term to describe his old beat up car:
"She is wore slap out so could you pick me up on your way into the office?"