methaporical code switching

Metaphorical code-switching refers to the tendency in a bilingual or multilingual community to switch codes (language or language variety) in conversation in order to discuss a topic that would normally fall into another conversational domain. "An important distinction is made from situational switching, where alternation between varieties redefines a situation, being a change in governing norms, and metaphorical switching, where alternation enriches a situation, allowing for allusion to more than one social relationship within the situation."[1] For example, at a family dinner (where you'd expect to hear L variety), family members might switch from L to H in order to discuss school or work. At work (where you'd expect to hear H) interlocutors may switch from H to L when discussing family.[1]

references:

1 a b c Gumperz, John Joseph; Dell H. Hymes (1986), Directions in Sociolinguistics: The Ethnography of Communication, Oxford: Basil Blackwell
2 Blom, Jan-Petter; John J. Gumperz (1972), "Social Meaning in Linguistic Structures: Code Switching in Northern Norway", in J. J. Gumperz and D. Hymes, Directions in Sociolinguistics, New York: Holt, Rinehart, and Winston
3 Ferguson, Charles A. 1959. Diglossia. Word
4 a b c Fishman, Joshua. 1970. Domains and the relationship between micro- and macro- linguistics
5 Fishman, Joshua and Laurence Greenfield. 1970. Situational measures of normative language views in relation to person, place and topic among Puerto Rican bilinguals. Bilingualism in the barrio.

adapted from: http://en.wikipedia.org/wiki/Metaphorical_code-switching