As part of the Dutch as a Foreign Language course, final-year students from the Faculty of Engineering at the french-speaking Université de Mons in Belgium annually organise an immersion day for themselves in the city of Leuven, situated in the Dutch-speaking region Flanders. This “amusing trip” is actually a well thought-out educational project, based on task-based language teaching and blended learning, a tool to reach the learning objective of the course: learning Dutch. This context increases their will to communicate by making their language productions useful and crucial : the project unfolds over the course of an entire semester and the responsibality is completely in the students’ hands: looking up information about Leuven unfolds the target language culture and the need for reservations and appointments puts them in contact with role models in Leuven and makes them achieve success experiences throughout the entire project. Since 2004, smartphones and Facebook have been part of the project. It creates competition among the students, leading to spontaneous (unsolicited) language production. The immersion day thus combines face-to-face interactions with locals and real-time computer-mediated text productions. In May 2023, however, the students shattered the formula by questioning the relevance of Facebook. This paper presents the principles which were taken into account to develop the project, as well as the different phases of the project. It also reflects on the further integration of social media and devices in language programmes or projects in the post-corona era.