noun. to give someone twos on a cigarette is to smoke half of it then give them the rest to finish. More commonly done by boys as it is less considerate.

verb. to "twos" a cigarette is to smoke one together, taking a couple of drags then swapping. More commonly done by girls.

Twos is a special word. While it can be used in relation to cigarettes, it makes more sense to apply it to joints.
It makes sense as a noun -
Adjective -
imperative -
verb
Basically the person who rolls it starts it - the person who has called 'twos' then gets it afterwards.

There is no threes or fours. It just flows from there.

when someone smokes a fag, you say twos to get half

An exclamation made to show ownership of a seat in a room. When getting up from one's seat, proclaiming twos leaves this particular spot branded by the one who was sitting in it until they return. Sitting in someone's seat after having called twos often times leads to both physical and verbal attacks. Twos must be called while still touching the seat and is invalid if called while standing up. In the instance that he who called twos is to take a seat anywhere else, twos is immediately cancelled and the seat is once again up for grabs. Twos is not valid if he who calls it leaves in a vehicle with expectations of getting their seat back when they return. One is allowed to take a bathroom break and call twos without the toilet counting as another seat.

How long a commercial break lasts; i.e., two minutes and two seconds.

Obviously

2+2=4

When you drink from 2PM until 2AM then promptly pass out.