This paper deals with the peculiarities of language code choice as a means of national self-expression in the Arabic social media humour (in particular, in memes and jokes). In the globalized online communities, humour can play a pivotal role for the rapprochement of in-group members based on a certain type of their identity (national, social, gender, etc.). In this study, the notion of Arab national identity refers to the entire Ummah and, on the other hand, to the representatives of different Arab countries as well. It is reflected on the Arabic language variation online and beyond. This research revealed diverse language attitudes conveyed within the “self – other” binary opposition. The analysis of over 1,000 online posts (Egyptian, Iraqi, Moroccan, and other) showed that the commonality with the in-group members is expressed with the language code which is considered the closest for the recipients. It is indicated to the predominance of colloquial varieties (territorial dialects, sociolects, youth slang) with the variation in their written transmission. Modern Standard Arabic is used as well, sometimes with minor deviations from the norm or with the colloquial lexis insertions. Both explicit and implicit lexical tools (colloquial and slang words, precedent lexis, etc.) are utilized to stress the uniqueness of “self”. Different codes are used to create the contrast between “self” (all Arabs / a certain Arab country) and “other” (all non-Arabs / the West / a certain Arab or non-Arab country, etc.). The studied varieties were also affected by the sociocultural context, topics of posts, communicants’ situational roles, the technology, and so forth. The results of this investigation ascertained that the Arabic language form used in the humorous posts is an integral part of the communicants’ identity as it demonstrates their belonging to a national group with its specific sociocultural, political, and historical background.