My wife would 'volunteer me' to fix, install, and paint things for people she knew. Installing a new car sound system, setting up an entertainment center, and installing cable were the most common. This was all without warning of any kind. I would get home after work with some strange car in the driveway. She would dismissively say, 'Oh yea, that's Tilly. She needs you to XYZ whatever.' No way to stop her from doing this. Because for her, it was nothing and it increased her popularity.
So, I got sneaky about it. There were two ways. First, I started taking forever. I would take two or three days to do a job which takes an hour. Finally, I started doing whatever job my wife volunteered me for, about 90%. It would work, but there would always be some little irritant that would drive them crazy.
After a month of peace I asked my wife what was going on? Turns out word had spread among her friends that I am unreliable. They didn't want me anymore. What a shame.
Heh. Being a tinker, and the son of a tinker, I never even thought of doing that... And in and amongst my contracted work and my many side-hustles, My old lady supplied an endless variety of things for me to do for friends, relations, and church members... all for free mind you, or if it was a big job, just for material costs and some small remuneration.
I never let the work suffer - I just got so busy that I had no time for family or for her. Really. Personal time was always hard for me anyway, always something on fire that I had to fix, and leaving go meant that fire would be a conflagration by the time I got back to it...
When she finally figured out that every time she asked me to do for someone else meant quite literally, precious time taken away from the family (because it really was the only way I could do it), she relented and her asks became extremely rare.