This study deals in its first part with presenting a brief overview of the most important characteristics of the colloquial/vulgar language. The second part is concerned with analyzing the phenomenon of omission and words that have been affected by the mechanics of omitting such as syncopation, agglutination and apocope. The study also shows the omission mechanisms that the writer uses in his novel Jarrapellejos de Felipe Trigo and that the aim of using them is to try to convey or simulate the real nature of the dialogues between the protagonists. Moreover, the linguistic forms mostly affected by omission in the novel are highlighted. Key words: colloquial language, vulgar language, apocope, syncopation