When a new concept, series of concepts, or the ensuing discussion of said concepts is so stimulating to the mind that one experiences a climactic mental state akin to the physical state of the orgasm; a mental orgasm. The experience is named for Carl Sagan, as it is through watching or reading his works that this experience is most commonly achieved.
I never knew the universe was so huge. Earth is just, like, a mote of dust, illuminated in a beam of sunlight, floating in the great cosmic ocean. Ooooh, oh man, I think I'm having a Sagasm!
Oh man, so amazing. It okay if I just fall asleep?