Today's Doonesbury comic strip includes a curious linguistic artifact. In panel two, a an engineering student describes herself and a partner: "We're engineering honchas, and the thing just sits there mocking us" (emphasis added).
The meaning of honchas is fairly clear. It is a (perhaps jocularly) feminine version of the word honcho, meaning "boss" or "hot shot". The final <-a> is an extension of the grammatical rule relating pairs of words such as Latina/Latino or norteña/norteño, where the first word in each pair is feminine and the second is masculine. All of these words are borrowed from Spanish.* In Spanish, as in many European languages, nouns and adjectives are categorized into classes commonly called grammatical genders. While Modern English does not have grammatical gender (except, arguably, in the pronoun system), English speakers sometimes use the feminine form of loan words when referring to women or girls - particularly with loans from Spanish.
What makes this particular formation interesting, however, is that honcho is not a Spanish loan word. It comes from the Japanese word 班長 hanchou, meaning group leader or patrol leader, and was probably picked up by US soldiers during or after World War II. The OED's earliest citation (spelled hancho) is from 1947; honcho is mentioned in the journal American Speech in 1955.
1947 J. BERTRAM Shadow of War VII. i. 212 But here comes the hancho. This boat must be finished to-night. 1955 Amer. Speech XXX. 118 Honcho. 1. n. A man in charge. (This is a Japanese word translated roughly as ‘Chief officer’, brought back from Japan by fliers stationed there during the occupation and during the Korean fighting...) 2. v. To direct a detail or operation.
While it is common for languages to borrow words from other languages, borrowing grammatical rules is less common (but certainly not unheard of). That seems to be the case here. The Spanish rule that a masculine noun or adjective ending in -o can be made feminine by changing that ending to -a is borrowed and applied to a non-Spanish word in English.
* Interestingly, in each case the Oxford English Dictionary cites an earlier date for the masculine version (Latino in 1946, norteño in 1953) than for the feminine (Latina 1972; norteña 1978).