a shot of life
Someone (or something) that gives you the urge to jump up and yell. They may not be the smartest, or the most attractive, but they are full of stupid, loud, and glorious energy. They are like a kid who just got a sugar rush and a punch to the gut.
My brother started a rap battle with the mailman. That was a shot of life.
The toaster exploded during breakfast. That was a shot of life.
My friend kissed a goat at the zoo. That was a shot of life.