The meaning of an idiomatic expression cannot be transparently worked out from the meanings of its constituent words due to its figurative and unpredictable nature. Consequently, the syntactic composition and the structural paradigm of an idiomatic expression are supposed to be the same in every context. However, this is not the case in the institutionalized second language varieties of English spoken around the world. In this regard, the present paper aims at showing that the input-oriented syntactic composition and structure of English idiomatic expressions undergo innovative processes such as substitution, addition, and deletion of lexemes or phrases in the grammar of L2 learners of English in Cameroon. This reveals that, the imageable ideas of English idioms do not call up the same conventional lexical and syntactic features in the minds of L2 learners. Every New English context has its rules of constructing English idiomatic expressions as the speakers strive to indigenize and domesticate the English language.