prodigall: wastefully lavish, foolishly extravagant, excessive. In the story of the Prodigal Son, Luke 15:11 -- 32, the younger of two sons asks his father to give him "the portion of the goods falleth to me" (Luke 15:12). He then journeyed "into a farre countrey, and there wasted his substance with riotous living" (Luke 15:13). Reduced to penury, the prodigal son worked feeding another man's hogs and had to live off the scraps of the pig's feed. He shamefully returned home in hopes that his father would hire him as a servant, but his father welcomed him warmly and "killed for him the fatted calf" (Luke 15:30). Orlando confronts Oliver with the parallels of this story, asking what he has done that is so prodigal that he should be denied his inheritance and still reduced to penury. 

penury: extreme poverty, destitution

Boy: a male person of low birth or status, rogue, wrench, hind, villain, peasant

elder: meaning a) older b) hostile c) an "asshole" or "shitty". "Elder" plays on "aisne" (silent 's') meaning eldest or first born, and asse, allowing for a possible play on "anus". A branch of the same name, the Elder Branch, has a strong smell and was commonly placed around bathrooms. Additionally, Elderberries were also used within a household to relieve diarrhea while elder bark was used as a purgative. So this word carries quite the subtext.

yong: after insulting Oliver with the term "elder" he calls him yong, meaning inexperienced.

Sir Rowland de Boys: Le Chanson de Roland ("The Song of Roland") is one of the most celebrated of the early epic French poems known as Les Chansons de Geste and Sir Rowland's best friend and adventuring partner was named Oliver. It is unknown whether this association was intended by Shakespeare, but the name Sir Rowland would nonetheless invoke images of chivalry and honor to Shakespeare's audiences. The name de Boys may have been inspired by Ludovico Ariosto's narrative poem Orlando Furioso or "Mad Roland". In this tale, Orlando finds the name of his beloved carved into a tree alongside that of his lover, goes mad with jealousy, and rages naked through the forest, paralleling the way Orlando will go on to carve the name of Rosalind throughout the forest of Arden.

raild: rant, rave, abuse, insult; meaning you attack yourself when you attack my birth.

obscuring and hiding from me all gentlemanlike qualities: keeping me ignorant of proper instruction in the accomplishments of a gentleman.

alottery: inheritance, allotment

testament: will

you shall have some part of your will: meaning that Orlando will have some part of what he desires/is requesting. But also, perhaps Oliver means to fulfill his will (lust, libido) by giving "Orlando's part" (division of the buttocks) his own part (penis) to "fuck him over".

grow upon me: become a nuisance to me, encroach, take liberties

physicke: cure, purge

ranckenesse: excessive wild growth; cure your insolence; remedy your luxurious growth; cut you down to size