What does “Thundering typhoons” mean?
What does "you blue blistering barnacles" or "Billions of blue blistering barnacles" mean?
Blistering barnacles is a "euphemistic oath" used by Captain Haddock, a fictional character in The Adventures of Tintin, who sometimes extends the alliteration to "Billions of bilious blue blistering barnacles!", for example.
It doesn't really "mean" anything, being just a made-up exclamation coined by the author (Herge) so as not to offend anyone. But it'll have become much better known (effectively, a catchphrase) since Spielberg's animated film version was released last year.
More specifically, barnacles are a kind of crustacean that lives on the bottom of ships and boats, and are usually considered vermin that get in the way of steering the boat. Captain Haddock, being a seaman, uses this as an expletive.