off-the-wallism

Maxの奥さん、the beautiful Gloria's parentsが日本に遊びに来ることになり、Max家の家族は、彼らをどこに連れて行くかで色々なアイデアが出してます。
"Let's take them to Disneyland," exclaimed the youngest Danger, an opportunist.
"Let's take them to Omote Sando," offered the middle child, a female and born shopper.
"Let's take them camping in Hokkaido," suggested the oldest offspring, a youngster in whom Max was beginning to recognize uncomfortably familiar off-the-wallism.
"Let's plan a cocktail party," added Gloria, "and invite all our new friends."
"off-the-wallism" が分からないので辞書を見ました。 "off-the-wallism" の項はありませんが、"off-the-wall" で次ぎの意味が載っていました。
・American Heritage Dictionary:
1. Very unconventional or unusual: manic, off-the-wall creativity; off-the-wall humor.
2. Exhibiting bizarre behavior; crazy: their off-the-wall friends.
・Merriam-Webster's Online Dictionary: highly unusual: bizarre: an off-the-wall sense of humor
・Wiktionary:
1. (idiomatic) Wildly unconventional; bizarre; absurd.: What kind of a harebrained, off-the-wall idea is that? : She is a very off-the-wall character.
2. (idiomatic) Greatly inappropriate.: His behaviour today is off-the-wall.
"off-the-wallism" は "ism" を付加して "off-the-wall" を名詞化した表現と理解しますが、ついでにOnline Etymologyの "ism" を見ると、次ぎの説明がありました。
suffix forming nouns of action, state, condition, doctrine, from Fr. -isme or directly from L. -isma, -ismus, from Gk. -isma, from stem of verbs in -izein. Used as an independent word, chiefly disparagingly, from 1670s.
著者のRobert J. Collinsは皮肉屋でもありますが、ユーモアのあふれる氏の文はとても面白いと思います。