The idiom "lightning fast" is used to describe something that happens or moves very quickly, almost instantly. The figurative or metaphorical meaning of this idiom is that the action or speed being described is amazingly fast and speedy, beyond what is expected or normal.

The idiom "toss-up" means that it is a decision that could go either way or it is uncertain which option will be chosen. It is often used to describe a situation where there are two or more equally favorable options and the person making the decision cannot determine which one to choose.

The idiom "set off" is used to describe an action or event that occurs as a result of another action or event. It can be used to describe both literal and metaphorical situations. In a literal sense, it means that something causes an explosion, fire, or other violent act.

The idiom "you're on" means that someone is about to start doing something, or that they have already started but are not yet ready to tell anyone else about it. It can also be used as a way of encouraging someone to do something or to congratulate them on starting something new.

The idiom "bated breath" means waiting or anticipating something with bated breath, which can mean being anxious, nervous, or excited to hear what is coming next.