A sonic boom is the sharp shock wave and loud crack produced when an object moves faster than the speed of sound. The important idea is threshold behavior: once motion crosses that limit, the surrounding air cannot adjust smoothly, so energy is released as an abrupt pressure wave.
In cyber security, the term is usually used as an analogy for sudden boundary-crossing events in systems, such as traffic bursts, overloads, or cascading failures. Attackers may try to push a service past its safe operating range with floods or rapid spikes, while defenders look for rate limiting, capacity planning, and anomaly detection to keep the system below that threshold. The lesson is simple: when a system is driven past a limit, the result can be immediate, loud, and hard to ignore.