As the name suggests, the Fibonacci cumshot is a trail of semen taking the same shape as a Fibonacci spiral. As impossible as such a thing appears, it is easily achievable by standing on a quickly rotating platform and bringing oneself to a violent orgasm. For better results, do so in the vacuum of space. Also known as a fib, or fibbing.
Chaz: "Babe, I guarantee that was a Fibonacci Cumshot!"
Babe: "There's no way you just fibbed!"