The world is witnessing an unprecedented growth of the English language worldwide. Now more than at any time in linguistic history people are powerlessly assisting the expansion of one global language, English, dominating other languages even in countries, such as Congo-Brazzaville, where its presence was not long ago barely observed. There has been a growing interest in studying the sociolinguistic change brought about by the lingua franca nature of English. English is increasingly used along other languages in Facebook communication. It is therefore important to thoroughly examine the main pragmatic functions of English/French alternation in a politically motivated Facebook interaction among Congolese users. In this study, a corpus of 265,147 words, including 9,330 comments were collected from October 2015 to July 2016, the time period highlighted by two major national political events, mainly the constitutional referendum (October 25, 2015) and the presidential election (March 20, 2016). The analysis revealed seven communicative functions (e.g., offering advice, astonishment, criticism, anger/cursing/insult, appraisal, hope boost and motivation, jocular mockery) trigger the use of English in politically motivated Facebook communication. The lingua franca function of the English language worldwide is on the top of the factors influencing and motivating Congolese Facebook users to resource to this language in Facebook interaction. The users tend to be driven by the mere idea that in order to put the communication on international scale, a global language is needed regardless of whether all fellow users understand it.