Some Persian colloquial idioms do not adhere to conventional syntactic structures and exhibit extrgrammatical motivation. The present descriptive-analytical study aims at investigating the extragrammatical motivations in Persian Colloquial idioms which involve the verb "goftan (to say)". The data for this study were extracted from the Persian Folklore Idioms (2008) and Sokhan Great Dictionary (2003) and analyzed within the theoretical framework of Filmore et al. (1998). The findings showed that extragrammatical idiomatic constructions were mostly formed through the reduction of the verb valency, seemingly conditional constructions, unconventional use of "rā" (often used as the object marker), unconventional occurrence of "ke" (often used as the relative and the emphatic pronoun), and the occurrence of the verbs in succession. In sum, extragrammatical idioms exhibit syntactic complexity due to their unconventional syntax and semantic complexity arising from the potential absence of readily identifiable underlying cognitive motivations such as metaphors, metonymies and conventional knowledge.