I was running on the treadmill at my university gym and this Portugeuse guy from halls got on the treadmill next to mine. His english was pretty poor but he insisted on having a conversation with me anyway, even though i was trying pretty hard (16 kph). I had to look across at him to try and understand what he was saying.
I missed the belt with my right foot and stomped on the non-moving edge of the treadmill instead. I got spun round, hit the side of the treadmill, fell, hit the belt and got spat out the back.
It's hands down the most embarrassing thing that's ever happened to me. I didn't know whether to get back on and finish my run or leave the gym in disgrace (i decided to finish the run, though my leg was grazed pretty badly).