Slow off the mark means exactly what it says. In Track and Field the runners are told, On Your Mark, Get Set, Go! If one of them gets off to a slow start then they are slow off the mark which is the line on the track where they are supposed to begin running. This represents an expression and not an idiom or slang.
An idiom is something that does not mean what the phrase says literally, so yes. You can't actually laugh your head off.
Ripped off means you had something stolen. You were robbed.
you was close to something,you almost got it
It is a fishing term. At first is seemed as if you were caught ( hooked ) but you escaped capture or consequence.
Usually this idiom is used in a battle or military application in which you remove the most dangerous opponent or the leader first, so that the other enemies will be easier to deal with.
An idiom is something that does not mean what the phrase says literally, so yes. You can't actually laugh your head off.
Ripped off means you had something stolen. You were robbed.
you was close to something,you almost got it
Talking excessively, usually spilling secrets.
It means to fall asleep while sitting (or standing).
Old sailing slang meaning to be no longer in danger.
Nothing. The correct idiom is "get OFF your high horse," meaning stop acting so conceited as if you are above everyone else.
You are alot like you mother/father/brother/sister.
Madagascar is not an idiom, it is an island off the coast of Africa.
the idiom of really upset is "pissed off"
This isn't an idiom because you can figure it out if you look up the word "pins." It is a SLANG term meaning legs, so you knocked him over.
I guess its an idiom and i don't know anything El's