Yahoo is a noun that refers to a noisy or violent person.

The word yahoo was invented by novelist Jonathan Swift in 1726 satirical work Gulliver’s Travels. A ‘yahoo’ was a term that described a made-up race of unintelligent, violent brutes. The word later came to refer to a crass or stupid person.

It pains me to say this, but when I first met Earl, he struck me as something as a yahoo. He didn’t seem very smart or sophisticated in his overalls and Nascar t-shirt, but when I got to know him, I realized that looks could be deceiving.