I should preface this by stating that I am not sure what kids these days are taught. I know when I was a young lad I was taught to never leave heavy machinery running unattended. This morning I learned that rule is not limited to heavy machinery.
Do not leave blenders unattended either. Especially if they are loaded with all kinds of tasty fruit, like raspberries, blackberries, strawberries, bananas, pears, because there is a very good chance that it will vibrate to the end of the counter and go crashing to the floor spreading a huge, gooey, purple mess all over your kitchen.
Second tip: when cleaning said mess remember that in this gooey mess are shards of glass, or very sharp plastic . . depending on the make of blender.
More tips as they develop.