Originating from the seattle area, this is a word that is used sarcastic to mean "no". It is most commonly used as a remark to a sarcastic comment someone may have made to the person saying yeep

“Yeep” is a term of endearment spoken by Amish folk from Chili, Wisconsin. Oftentimes, if you strain your ears and quiet your thoughts, you will hear a softly spoken “Yeep” as two buggies pass each other on the gravel road at night.
The word originates from the era of the great divide between the ruling regimes of the Amish Nation. The Stutzman family, known throughout the community for their prized sheep, stole a secret recipe that had been handed down from mother to daughter since the beginning of Amish time. The Yoder family, distraught with the loss of this age old recipe, stormed the gates of the Stutzman farm, proclaiming “thou shall deliver the scroll of Yoder henceforth to the rightful hand of Edith or we shall strike down upon thee with great vengeance” Ura Gingerich (neighbor of Stutzman’s and oldest of the Elders) heard the commotion and exclaimed “Yeep!” then called forth the families and demanded the Stutzman family sheep be placed in the care of the Yoder family. The Yoder’s took off with the sheep under their arms.
The word is a mix of two words, Yoder and shEEP. The recipe formerly known as “Yoder Vittles” is now marketed throughout the village as “Stutzman Sticks” The families share an uneasy peace between them, but there have been “incidents” lately hinting at another civil war. Elders “Yeep” at each other to remind themselves of the troubled times the community has suffered in the past. Ida Gingerich was quoted as saying “To Yeep at someone, is to ...

yes

yeep-an expression of one's disbelief or notion of absurdity yeepy-(adj) outrageous; unbelievable; absurd; ridiculous yeepert-(noun) one that is yeepy

Another word for yep.
Originally formed from elongating yep (like yeeeep), yeep is better if you're feeling particularly happy or cheerful.

A person of Jewish ancestry.

The sound a Flower Turtle makes.