At the restaurant I used to work at there was an extra upstairs room for special parties and the like. It had a spiral staircase and a large round table sat directly below the staircase.
One day a big party came in and wanted to sit upstairs. Everything went great, although it was annoying taking large trays of food up a spiral staircase.
Once the party left upstairs i began to clean up the room. I was taking dirty dishes down in tubs and glasses in racks. Finally, there were just a few full pitchers of water.
My tray was wet and I knew the pitchers might slide around on it but I put them all on there anyway so I didn't have to keep coming back up and down.
I was at the top of the staircase and the pitchers started to slide around.
One slides straight off of the tray and dumps its entire contents of icy cold water on an elderly woman's head at the table below the staircase.
I think the pitcher even bonked her on the head for good measure. She said my look of horror alone was apology enough.
All of my coworkers were ruthless about it, saying things like I tried to make a waterfall installation and what not.
TL;DR- I accidentally soaked an old lady with an entire pitcher of cold water at work.