Typically experienced when one is giving fellatio, and places the penis in their throat/towards the back of their mouth. The receiver cums, and knowingly or unknowingly, the giver is unable to keep up with the flow of cum. As a result, the cum overflows into the giver's nose, and begins to exit the giver's nose. The receiver may or may not get nose cum on their person.
While Jennifer was blowing her boyfriend, she realized his immense amount of cum had caused her to get nose cum and accidentally get some on her boyfriend.