The aim of this study is to gain insights into students' language use on social media as part of the specific linguistic activities of second language (L2) learning, including development of sociopragmatic competence. Two Facebook groups were introduced in different English-as-L2 classes that were part of an international collaborative project comprising secondary schools in Colombia, Finland, Sweden and Taiwan. The study is theoretically grounded in sociocultural perspectives on learning, and the methods involve logging the students' linguistic interactions in the social media groups. The analysis of the empirical material explored how the students framed the activities by different types of keying in their choice of linguistic repertoires. The findings show that the social media context offered a casual space for communication in which the students, by attentively attuning to the local coordinated framing, used diverse linguistic repertoires to play with the language. In instances of upkeyed framings, the language play was not only used with pragmatic intentions, but also as a means for various socializing purposes. In conclusion, it is suggested that language play on social media can be seen as a valuable activity in developing sociopragmatic competence to prepare students for L2 use outside of school.