Regular irregularity. On contextual meaning of grammatical errors After the consideration of possible grammatical playings in agglutinative Finno- Ugric languages I survey the utilization of those in some jargons and lingual layers and roles of lingual playings and riddles in group's cohesion and stylistics. In opposition to views of purification of usage I deal with positive cases of irregularity, with conscious and constructive ones. With appearance of lingual intellect in ungrammatical usage (conscious contravension) and communicative worths of associative techniques. The enigmatical and playfui use of grammar is a long-standing typical and fruitful phenomenon in Hungarian usage like an illustration of lingual creativity and intelligence. The grammar's possibilities of light (entertaining), identifying and creative use are evoked and illustrated by examples.