It also appears in his laundry room.in "Dumped" as a clothing wringer, however this is different from the one kept in his bathroom.
The wringer plays a very important role in the episode "Stuck in the Wringer." SpongeBob slips on his soap and gets stuck in it, and this causes him to have a mishap-filled day. His problem only becomes much worse when Patrick uses his Forever Glue on it to make him even more stuck due to his stupidity.
Near the end of the episode, SpongeBob and Patrick cry tears as a result of their friendship declining, which melts the glue and frees SpongeBob. Once he is freed from the wringer, SpongeBob throws it up into the air to give Patrick a hug in celebration of their reconcilation, however, it lands and traps both of them in it, though this doesn't affect the pair since they are at least glad to be stuck with each other.