A good deal for the Caravan

1) Boy: Tommy: "Now that''s a good lad! *seconds later*...aren't you gonna get him for me?"

           Boy: "Yeah"

           Tommy: "Well what are you waiting for?"

           Boy: "The five quid you gonna pay me."

           Tommy: "Well fack off then, I'll find him me-self"

           Boy: "2.50!"

By immediately assuming that he was entitled to Tommy's money in exchange for his favor, the boy exercises a sense of power: he's attempting to take control of the situation through the manner in which he speaks, even though it wasn't exactly successful. 

2) Tommy: "Degs?...Ah, dogs. Yeah, sure, I like degs." or "Now that's a good lad." Tommy expresses superiority by purposely repeating Mickey's grammatical mistake after he had already corrected him, or by addressing the boy in a patronizing tone, as if he was a pleasantly obedient deg. 

3) Mickey: "Fuck me! Look at the size of him. How big are ya? Hey kids, how big is he? Hey ma! Come look at the size of this fella." Now I know it doesn't seem like it, but for those who know the movie Snatch, you'd know that Mickey is actually using his words in a manipulative and ultimately sarcastic way. You see, in the next scene, Mickey challenges the "big fella" to a fight. To the audience's surprise, Mickey casually gets up after every throw, and knocks his rival to the ground with a single punch. He therefore used his language to indirectly mock the big fella. 

4) Mother: "See if the fella wouldn't like a drink!"

    Tommy: "Ahh, I could murder one." 

    Mother: "Ain't no murdering done around here I don't mind tellin' ya" 

By failing to recognize Tommy's metaphor and taking his expression literally, the mother expresses a general lack of knowledge. This contributes to her powerless outlook, while making Tommy appear more educated. 

The narrator of the movie also notes: "Their park is well known for a school of negotiation and business, it's part of the reason why they talk like they do. So you can't follow what's being said."

 The observation suggests that, when used (and taught) in the right way, language can easily be manipulated and result in a general source of self-interest.