A play on the word "ecstatic" but quite the opposite, as it is the joint use of the words sex (intercourse) and static (unchanging).
It is when the male decides to awkwardly troll the female (or actually has a condition of sexstaticism) during sex by making only the same monotonous sound for every pelvic thrust. Each sound must be identical in pitch, volume, tone, articulation, and resonance - even at the climax.
It MUST last the full duration of the sexual activity, whether that be 5 minutes or an hour. After a Sexstatic performance, it is to not be talked about and pretended as if it never happened.
NOT Sexstatic: *during sex* oh...ooooh...OH!....OH GOD!! AHHHH!!! **** MY BRAINS OUT GERTRUDE!! AS HARD AS YOUR PARENTS FUCKED YOUR NAME UP!! *climax* Ooh...I love you gerdy...
Correct: *during sex; in a deep/low pitch, any volume, and dry, unchanging tone.* Ah.....Ah.....Ah.....Ah.....Ah.....Ah....*climax* Ah.....
Oh em gee, I couldn't sleep last night because my boyfriend was being Sexstatic and it was fucking weird.
To be hystatic means to be so overjoyed, that you have now become a combination of the words hysterical and ecstatic. When the Jersey Shore producers asked Deena to define it, she replies: "Hystatic is, you know, when you're like super happy, and like, really happy."