to have sex. "horizontal" as in lying down, having sex, but doesn't necessarily mean having sex when lying down.
"Lets get horizontal, baby!"
Usually occurs during a bout of food-poisoning or a night on the beers which can lead to severe pains and abnormalities relating to excretion. Upon going to the toilet for a dump, rather than fall vertically from your backside it will spray, or release horizontally. Called 'doing a horizontal'.
"You might want to be careful when using the toilet, I've just been for a horizontal"
an object or line that is ;
1) on its side
2) on its back
Person 1: "hey do you know how i remember the word horizontal?"
Person 2: "No, how?"
Person 1: "Because whores are always on their back"
Sleeping or lying down
Gosh i'm so tired I really wanna be horizontal right now!
to be passed out...usually frum drinking but jus plain asleep can qualify also
"I drank so much saturday night, i was totally horizontal all day sunday."
An insult, meaning extremely boring, almost to the degree of being asleep, like you're talking with a person that is comatose.
That guy is so horizontal, I thought my blank stare was going to get stuck on my face and I would forever be under suspicion of being a serial killer.