a shot of life
A human or object that is like a loud, messy, and slightly ridiculous party. They are not always good looking, but they are always loud, and they make everything around them feel like it's about to explode.
My dad started singing opera in the grocery store. That was a shot of life.
My friend threw a water balloon at a cop. That was a shot of life.
My toaster started talking to me. That was a shot of life.