noun Used to describe a situation when there's been a nuclear meltdown at a power generating facility. Derives from the state where the reactor core has fallen out of its protective shell (a critical situation).
It's a variation on the urban term four-on-the-floor.
When a person is so stressed, furious, enraged,mad, livid, superfluous with anger that they are about to pop. Thus, they are at the brim of their core.
During sexual intercourse, when the male assumes the missionary position, one arm is placed behind his back and the other arm is used to brace his body weight. The male then thrusts his pelvis whilst extending/flexing his brace arm resulting in having larger triceps than biceps.
Did you see Aaron's arms? His triceps are huge! He must be doing the Corey Anders with his old lady!