the.com/fever pitch

means The point at which excitement, anticipation, or agitation reaches its most intense, almost uncontrollable peak.

from Borrowed straight from medicine — a 'fever pitch' is the peak temperature of a fever, the highest point before it either breaks or does damage. By the 19th century, writers had lifted 'pitch' (already used since the 1500s for the topmost point of anything, like a roof's pitch or a falcon's flight) and paired it with 'fever' to describe crowds, passions, and excitement running as hot and dangerous as a sick body's temperature spike.