I'm guessing it's an Americanism. Sorry about that to the rest of the world ;)
"Carping" is slang for complaining about something. ex: He was carping about the wait for a table. "Croaking" is slang for dying. ex: Your pet fish croaked last night
They were rare in my youth, and outside of Perl, I haven't heard them used in probably 30 years.
Update: Just for kicks, here are some synonyms for "carp" from the Merriam-Webster dictionary: bellyache, bleat, caterwaul, croak, fuss, gripe, grouse, nag, whine, and whinge. It could have been worse.