Definition #2 - The underside of a typical male testical. Commonly known for being darker than the males scrotum. When people refer to "Tessius", they often do so without realizing it.
Definition #3 - The act of covering one's cock in shit and puke.
Bitch 1: Did you just see that big fat fucking Tessius?
Bitch 2: How could I fucking miss it? I heard it giving a sermon as it walked by.
Example given for definition #2:
Dude 1:" Hey bro, ima suck you dick cuh. Then ima lick yo Tessius."
Dude 2: "Fuck yes. You know me too well!"
Example given for definition #3:
Hick 1: "So I was telling this dumb blond to shut the fuck up and she pulled a Tessius after I shoved my dick in her ass and pulled out in just enough time for her to eat the shit off of it. She vomited all over my cock.
Hick 2: Did she finish?
Hick 1: You fucking know she did.
Hick 1 & 2 high five.