also: ったらない
expression
extremely; nothing more ... than this; as ... as can be
Colloquial expression attached to the て-form of adjectives and verbs to emphasize an extreme degree, often with a negative or exasperated nuance. Similar to といったらない.
彼の話はつまらなくったらありゃしない。
His story couldn't be more boring.
この部屋、暑くったらないよ。
This room is unbearably hot.