Not exactly DIY but when I was an apprentice we were doing a loft conversion in the Old School House in Wiswell. I was up in the loft and stood on a hammer that had been left on a joist, slipped off and both my legs were hanging through the ceiling of the utility room where the house owners were having their breakfast.
I lowered myself through and apologised for dropping in, which at the time I thought was quite funny in the circumstances.
My boss (a quick tempered sort of fella) instantly sacked me on the spot to which I replied "you'd better take me home then" as I was too young to drive, so he instantly re instated me with a severe bollocking. 😁