Becky Has A Long History In The U.S.

“Becky” actually dates back to the 19th century.
Cara Kelly writes how the name Becky has become a stand-in for a generic woman, generally white, who is familiar with sexual acts. The history of the name, and the connotations associated with it, dates back to the 19th century.
Origins of Becky
The cultural references date to William Makepeace Thackeray’s satirical novel “Vanity Fair” published around 1847. The protagonist, Becky Sharp, is a social climber who utilizes her charm and ability to seduce wealthy men in order to climb the social ladder. It’s the classic character of low class living on her wits in a corrupt society. In this case, that involves identifying men who stand to gain massive inheritances and convincing them to marry her in secret. She also has few female friends, and the ones she does have she tends to screw over.
Fast-forwarding to 1876, Becky Thatcher seduces Tom Sawyer with her “yellow hair plaited into two long tails.” Though Becky in Mark Twain’s world is less conniving and more a symbol of an unattainable, beautiful girl, it’s the start of a trend.
In 1938, Daphne du Maurier sets up the ex that will haunt us all in her novel “Rebecca“. Though not the shortened version of the name, the book and the 1940s Alfred Hitchcock-directed film adaptation cement Rebecca in pop culture as the name of the woman who will always be in a man’s head.
Becky Today
Skip ahead to Sir Mix-A-Lot, who adds the phrase “oh my god Becky, look at her butt,” to the cultural lexicon. The lyrics to “Baby Got Back” indicate Becky and her friend are white, somewhat basic and mildly racist, as they do not understand the appeal of a woman’s shapely posterior or wider definitions of beauty than their own. And thus adds the connotation that a Becky has a narrow, condescending world view, and we’re graced with the idea of a “dumb Becky.”
Things get very NSFW in 2010 when rapper Plies takes the concept further. His song “Becky” is cited as the start of the name’s use as slang for a specific sexual act, not just a stand-in for a sexual woman. And in this connotation, an act that is believed to be favored by white women (we’ll let everyone debate this last part amongst themselves).
The meaning of the term at this point in time, and likely the one Beyoncé was invoking, is a bland, generally-white, woman, who may or may not be scheming to further her social success and wealth, likely by using her beauty and sexual acts to do so, all while having a narrow world view. Iggy Azalea and others have deemed the term racist, but analyzing the history of the term and understanding the definition of racism, that doesn’t seem to be the case.