Maxwell's face hardens, those chiseled features looking like they really are made out of marble. "Why'd I bring back train whistles? Why the fuck would I not bring back train whistles? I don't remember your ass giving me a shopping list. If you were awake this whole, you could've said something, and I would have picked up supplies for you while I was out. But you didn't. So I got my food, and I saw some train whistles that I bought. Now, I'm going to weld these to my gauntlets, and name my fists the Pain Trains. You can't imagine how long I've wanted to use that joke." All of this is said with a completely straight face. No hint of a grin or anything. 

"Also, now that I'm back and have MY shopping, you can go shopping on your own. Because I can't be bothered to help you while I'm hungry. I need to go through a hell of a lot more calories than normal people, so all of this food actually is useful. If we run into something strong, and I get hungry, well we're shit out of luck. I don't know what my caloric output is, but it's huge. So you can eat a dick." Maxwell takes a strip of well marbled meat out of the pouch and just puts it right in his mouth. "Mmmmm, that's really good." He chews happily, the meat actually cooking inside his mouth. One of the side effects of having the Purging Flame inside of him is that his body heat is off the charts. When Maxwell bleeds, he bleeds hot. Like, boiling hot. And the inside of his mouth is easily over 400 degrees, cooking things as he chews. 

"However, we'll get no where from being rude, so while I won't help you with shopping right now, I will do things to the best of my ability here. Give me a list of things to do, and I will try to fufill it as I can. I would like to not be here for very long." Maxwell does this out of necessity, not kindness. If he didn't need LeeRoy's ship, he wouldn't hesitate to get into a sass battle/dick waving contest with LeeRoy. He can sass with the best of them.