The idiom "rocket science" is used to describe a subject or task that is extremely complex and difficult to understand, especially for someone who is not an expert in the field.

The idiom "nail biter" refers to a person who is very anxious or nervous before an event or situation that may affect them greatly, such as a performance or a test. It comes from the idea of biting one's nails nervously or anxiously.

The idiom "in the bag" means that something has been secured or guaranteed. It can also mean that a deal or transaction has been completed successfully.

The idiom "close, but no cigar" means that something is very close to being what you want or need, but not quite there yet. It implies that it's almost perfect, but not quite.

The idiom "up the ante" means to increase or intensify something, typically by adding more resources, effort, or skill to a situation. It can also mean to raise the stakes or elevate the level of something, such as a game or competition.