You may be looking for either Mary-Beth Maybell from Grand Theft Auto: San Andreas or Mary-Beth Williams from Grand Theft Auto: Vice City Stories.

Mary Beth is a character mentioned on the Rednecks promotional website for Grand Theft Auto 2. Her father is Pa Wayne and she has many siblings, which include: Bob, Joleyn, Jethro, Seth, Lazy Balls, Peter Lee, Boff, Sammy Jo, Teri Barbara, Maggie May, Bonny, Jonny W., Billy Bob, Bobby Bill and Fabrizio.