Gibberish usually uses the English language, and this is how you speak it...

ONE SYLLABLE

001.
Take the first letter of a word and add "-ither." Other dialects use "-itug," "-idig," or "-atheg."

Ex.: Dog begins with "d," so we take "d" and add "-ither" to get "dither."

002.
Take the rest of the word and add "g-."

Ex.: the rest of "dog" is "og," so when we add "g-" it becomes "gog."

003.
Put the two parts together.

Ex.: Dog becomes "dithergog."

TWO SYLLABLES

001.
Split the word into it's two syllables.

Ex.: Menace becomes "men" and "ace."

002.
Translate each syllable separately, like they're each a one-syllable word; i.e. add "-ither" (etc.) to the first letter, "g-" to the rest of the word, and then put them together.

Ex.: Men becomes "mithergen" and ace becomes "aithergce."

003.
Put the syllables together.

Ex.: Menace is "mithergenaithergce" (or "mithergen-aithergce).

For more syllables, split them up like for two syllables, and translate each syllable like it's a one-syllable word.

Can you decipher these?

01. Eitherggg

02. Mithergailmithergan

03. Bitherganithergaithergna

04. Aithergntaithergrtiithergca

the answers...

01. Egg

02. Mailman

03. Banana

04. Antartica