I wouldn't be caught dead in sleeping during the class.
The idiom is "dead certainty". It means it's in the bag = this is a dead certainty = this is cinch
get scared or terrified
It is actually an idiom.
Nothing. I believe you mean to run out of STEAM, which means that your "engine" doesn't have any "steam" in it - you've run out of energy or drive for something.
This is not an idiom. Idioms make little or no sense unless you know the definition. This sentence makes perfect sense, so it is not an idiom. The dead fish smelled so bad that even as high as Heaven, you could smell them.
To be 'as dead as a donut' is to be utterly dead, devoid of life (when applied to people, plants or animals) or finished with, unusable (when applied to inanimate objects).
The opening line of the book, "Old Marley was dead as a doornail." Dead as a doornail is an idiom.
Things tend to be quiet at night, as if they were "dead." So if something is "dead as night," it means it is very quiet, not moving around, not making noise.
Nothing
They are implying that they have "killed" you - you are in big trouble with them, and they are going to make you pay for whatever you just did to them.
The phrase "laid eyes on" is an idiom.