ALT This study examines the pragmatic functions of fuck among British English teenagers in casual conversation in two corpora from the 1990s and 2010s. It applies a corpus-pragmatics approach to explore how the ongoing weakening of fuck in the perception of young speakers is realised in usage data. The major functions observed involve a predominance of idiomatic, emphatic and emotionally expressive functions. Conversely, usage associated with potentially abusive functions, including literal reference to sexual intercourse, is infrequent. Our observations are interpreted in the context of delexicalization and related diachronic processes, whereby contemporary usage of fuck among teenagers is characterised in terms of semi-delexicalized, pragmatically strengthened usage with weakened taboo status. The article evaluates the interpretation of idiomatic usage from a functional perspective, and contributes to methodological considerations of the use of spoken corpora for pragmatic research.