Usually used when describing a child who's only topic of conversation is of a sexual nature, ie the genitals , sex and milf spotting. A common insult for most teenagers, used instead of dickhead a form of jennan but used in a more sexual manner. The most common jennantalia will name theirs or close friends sexual anatomys and there phone will be loaded with cheesy, awful songs such as 'the ladies bras' and 'show me your genitals'
'Jack named Laurens boobs, hes such a jennatalia'
'oh my god, ive been jennantalia-afied'