Zappai (雑俳) is a form of Japanese poetry rooted in haikai. It is related to, but separate from, haiku and senryū. The Haiku Society of America refers to zappai as "miscellaneous amusements in doggerel verse," although a more accurate definition might be, as Lee Gurga suggests, a form of poetry that "includes all types of seventeen syllable poems that do not have the proper formal or technical characteristics of haiku."
References
Zappai Wikipedia(Text) CC BY-SA