“Oh no, I'm sure I can handle it,” was his continual reprise. First, when the drain was clogged. Then, when the caustic chemicals he was using began bubbling back up towards the kitchen. Again when the floor was covered in lime, eating through the mop he was trying to use to clean it up. You couldn't fault his confidence, or his collected nature, simply the results of his actions.
“Stop it,” you would say. “We should call a professional.”
“Oh, no, we don't need to pay a plumber for this. I'm sure I can handle it.”