Frankly, the sandwiches looked gross as shit. Like big, sopping wet slices of an underwater sea creature, bleeding stale green juice over an otherwise delicious-looking PB sandwich -- the kind that Mom used to make. However, as every teen movie since the early 1980s has taught us: we shall not judge books nor people nor sandwiches by their gross-ass covers.
When Tony bit into his sandwich (I waited for him to do it first, obviously) he whispered a simple "Oh boy" to no one in particular... I think he was talking to the sandwich, which he was clearly enjoying.
When I did the same, I realized what he was "Oh boy-ing" about: this disgusting garbage sandwich was actually... good. And not just "good for a pickle sandwich" good. It was genuinely enjoyable. The crisp, sour and tangy taste of the pickles cut through the savory, sweet unctuousness (thanks for the new word, guys!) to create flavor combo not unlike the way pickles complement the taste of a ketchup-laced cheeseburger, without overpowering it. I happened to say "oh boy" myself.