Zany describes people or things that are very strange and silly.

// The cartoon series centers around two zany characters, best friends who also happen to be space aliens, constantly amusing each other with outrageous antics.

Cadence is used to refer to various rhythmic or repeated motions, activities, or patterns of sound, or to the way a person's voice changes by gently rising and falling while they are speaking.

// Ivy relaxed at the beach, listening to the cadence of the surf.

// He speaks with a soft Southern cadence.

Something described as frenetic is filled with excitement, activity, or confusion. The word is a synonym of frantic.

// The event was noisy and frenetic, which prompted us to leave early.

To scrutinize something is to examine it carefully especially in a critical way.

// I closely scrutinized my opponent's moves before making my own.

As an interjection, eureka is used to express excitement when a discovery has been made. When used as an adjective, eureka describes something (typically a moment) that is characterized by a usually sudden triumphant discovery. 

// After years of trying to piece together a concrete business idea, I had a eureka moment and everything made sense.  

Jejune is a formal word that means "uninteresting" or "boring." It is also used as a synonym of juvenile to describe things (such as behaviors, attitudes, etc.) that are immature, childish, or simplistic.

// The movie adaptation employed surreal visual effects to tell the story, making the plot, jejune in the novel, archetypal rather than artless.

// The professor made rude and jejune remarks about the students' artwork.