すぽっと

1. 1snugly (into hole, container, etc.) ; tightly (fitting, covering) ; firmly Translated by Jiyomi
2. 2(with a) pop (i.e. sound of a cork, etc. being pulled out of a hole in one movement) ; with a plop ; (fall) straight

Other writings and readings

JMdict entry 2653550. Source and licence.