| Quote #1
Now, I'm no virgin to liquor, but moonshine is another beast entirely. It burns hellfire through my chest and head. I catch my breath and fight back tears, staring Camel straight in the eyes even as my lungs threaten to combust. (2.157)
Jacob seems to think that in order to appear masculine in front of Camel, he can't show how the "moonshine" affects him, no matter how much it "burns hellfire." Jacob sucks it up and tries to pretend like it's no big deal, even though he's feeling like he might explode on the inside. This is classic male insecurity if we ever saw it.
| Quote #2
Gentlemen, if you're a red-blooded American, if you've got manly blood flowing through your veins, then this is something you don't want to miss. If you'll follow that there fella – right there, just right over there – you'll see something so amazing, so shocking, it's guaranteed to [ … ] (3.122)
The implication here is that any guy who doesn't give in to this sales pitch isn't "a red-blooded American" and doesn't have "manly blood." You can see how this would work on a bunch of guys who are already at the circus to escape their downtrodden lives. In order to prove their masculinity, the customers are asked to pay up and view the "amazing" and "shocking" exhibit.
| Quote #3
I'm glad nothing requires my intervention, because I'm trying hard to maintain my composure. This is the first time I've ever seen a woman naked and I don't think I'll ever be the same. (3.195)
From the first time we meet him, the younger Jacob is concerned about his lack of knowledge about sex and how it's interfering with his ability to grow up. At the circus, he starts to fill in the gaps.