You Know What Happens If You Pee on a Worm (ミミズにおしっこかけると腫れるよ, Mimizu ni oshikko kakeru to hareruyo) is the forty-second episode of the Gintama anime.
Teaming up with Umibozu, Gintoki takes down the alien to save Kagura while trying to avoid the attacks of the Shogunate.
Umibouzu rushes to the injured Kagura, enraged about the fact that Prince Hata and Jii did not help her even after she saved them and is about to attack them, when he is quickly stopped by Kagura, who tells him that he should not hurt them after she saved them. Kagura asks him if she finally managed to change before the alien attacks them and tries to eat them. Umibouzu protects his daughter but loses his left arm in the process. Kagura is thrown away and before she can do anything; she is grabbed the alien and is about to get eaten. At the last moment Gin and Sadaharu emerge from the beast and Gin tries to reach Kagura without success. Gin and Umibouzu work together to unite their fierce attacks on the monster to free Kagura. In the meantime, the Shinsegumi try to attack the monster joined shortly by Bakufu warships, which are led by Matsudaira. The alien withdraws back to the ship to fully concentrate on Gin and Umibouzu when its nexeus, the alien's core bursts out of the ship growing large from the Terminal's power sources. As they are about to attack it, they witness that the Kagura is swallowed in the core and they can no longer attack it or they will kill her as well. The warships are ready to attack the alien not minding about Kagura, so Umibouzu is prepared to die with his daughter. Gin, however, asks from Umibouzu to trust Kagura and 5 minutes to save her. He gets swallowed to the core as well and tries to reach Kagura's subconsciousness to wake her up. At the core's surface, Umibouzu is joined by Shinpachi, Sadaharu, Prince Hata and Jii all trying to protect the core just for a little bit. The warships are ready to fire their cannons, when Kagura wakes up and breaks through the core with an uppercut to Gin. Matsudaira pushes the button to fire the cannon even if there are still people in the vicinity of the area. Umibouzu gets in front of everyone and absorbs the blow with his umbrella. With the alien defeated, Gin and Umibouzu are peeing on its dead body and have a conversation about the real reason that Umibouzu left his home. His left arm was prosthetic, so he could replace it easily. He originally lost it to his son, Kamui. His son is the real personification of fighting spirit according to him and was trying to revive an old tradition of the Yato clan called "Parent Killing". This was about the children surpassing their parents in power by killing them. Umibouzu was attacked by him and lost his arm, but he quickly bested him and was about to kill him. However, Kagura stepped in and stopped her father from killing her brother. Umibouzu realized that he was really trying to kill his son and he was afraid that he would do the same thing if Kagura decided one day to attack him just like his son. To protect her he left from his home leaving his wife and daughter alone. Gin passes him the letter that Sadaharu sniffed from his kimono in the last episode. It is a letter from Kagura towards Umibouzu, but since he never had a standard address it was sent back to the Yorozuya along with the rest of the letters. Gin comments that Umibouzu is very lucky that he has a family and advises him to cherish what he has left. Gin also mentions that he never had a family but he understands Umibouzu very well. Kagura and Shinpachi were overhearing this conversation and are moved by it with Shinpachi returning to the Yorozuya. Umibouzu tells to Kagura that he will cherish her from now and on and goes on to leave from Earth. Kagura tells him to wait but he continues to move on. As he is walking away, we hear what Kagura wrote in the message. She was writing about her whereabouts and how she believes that she can change in Edo inspired by the samurais there. She finishes the letter saying that when she changes, she wants to join her father on his travels and become the top alien hunter. When the narration ends, Umibouzu sheds tears saying that he will wait for her.
- Sakata Gintoki
- Okita Sougo
- Kondou Isao
- Prince Hata
- Hijikata Toushirou
- Matsudaira Katakuriko
- Shimura Shinpachi
- Kamui (flashback)
During the scene when Matsudaira was shooting the cannon after Gintoki and Kagura's dad (Umibouzu) has destroyed the alien's nucleus, the background music seems to play "Star Wars - The Imperial March" .