This is a horses equivalent of a orgasm. In some hick towns in America where sleeping with animals is accepted, boasting in the bar about giving your horse a "Maregasm" is quite common and completely acceptable.
Cletis: I gone and got me a new horse called Betsie, She's a beauty, it took me a while but i gave her a "Maregasm" she aint never gonna forget!
John Boy: Way ta go Cletis, you a lucky man!
America's next top stripper or exotic dancer. Will probably become a sex addict but I love her anyway. I mean really..who comes up with a name like that while in church? Everyone refers to her as this name at school there are some that think her mother actually named her this.
Have you met Morgasm Sellersexual? She is in my english class and cranks that lion king all day long