This term is used to describe a girl of interest who more likely then not is a little slutty or is down to fuck. (But warning some biddys are fucking teases and do not want to fuck or give head this is a term known as a bad biddy. Stay away from those!!!) There is no exact age for a biddy they can be from 14 and up. This does not mean that the girl has to be pretty, interesting, or actually fun to be around as long as she is fuckable and wants to fuck she is therefore a biddy.
-Dude are you bringing your biddy to the party this weekend.
-Dude we need some bids here i haven't got my dick wet in a minute.
-Fuck man some biddys would be nice right now.
"is that biddy wearing uggs in the summer?"
However, "biddy" in this sense might have died a welcome death had it not been for the influx of Irish immigrants into the U.S. in the early 19th century. Young Irish women often had their passage paid by upper-class American families, for whom they would then work as domestic servants while they paid off their debt. The practice was so widespread that such women came to be known as "Biddies," from a shortening of "Bridget," a common Irish women's name. This use of "biddie" reinvigorated the word, and ever since it has been employed by insolent children to torment their elders.
Sometime in the last 20 years or so, the term was recycled to mean a woman of any age. The connotation may exemplify the earliest expression synonymous with the concept now known as MILF.
"I'm trying to pick up a biddy"