Jack literally can't get wet, the second he touches water, it freezes. It never used to be a big of a deal, but then the guardians came along, and now he was forced to really make a big deal over it.

Jack's been on his own for a long time. He's used to snatching what food he can to get by, but now that he's on the Nice List, that option's off the table. The winter spirit takes it in stride - even when it means he doesn't get very much to eat - but when the other Guardians find out, they think it's a much bigger deal than Jack does.