Anguirus and Rodan were very worried about the state of Godzilla's health. He had a terrible bowl condition and had been unable to poop for five years. After trying to feed him on all his favourite foodstuffs like humans, dolphins and giant yeti, Godzilla still hasn't defecated. Rodan asked Mothra what she did when she had constipation and Mothra said that she looks at Battra's face and that's enough to make her shit herself. Rodan went and asked Anguirus who said that he just ate some grass and that makes him puke up his shit.
Rodan tried Anguirus's suggestion but all it did was make Godzilla hurl normal puke all over Ogasawara Island (which is where Godzilla lived in Destroy All Monsters). After Manda and Baragon had spent twelve hours later Godzilla had stopped being sick but was still horribly constipated. He didn't have enough water in him anymore so the poop was like stones and was causing his colon a LOT of pain.
The human scientists stationed on the island had also noticed Godzilla's predicament. They had seen how sluggish and puffed out with farts he had become and weeks of theorising had just led back to the same conclusion. Godzilla needed a poop. So they brought out 87 fire hoses and positioned them near his bus-sized asshole to give him a massive enema to propel out his feces. The scientists rammed the hoses fifty feet deep into Godzilla's colon - several of the scientists dying in the process, mostly due to stench.
They turned the 87 fire hoses on and Godzilla leapt into the air as water mixed with fecal stuff came flying out of his mouth. The pressure of the enema was so great it had forced water the wrong way through Godzilla's whole digestive system! The poop issue was sorted but now Godzilla was mad and trampled all the scientists to death. Bits of car sized solid poop crushed others too and some gave Rodan a headache after falling on his head. Godzilla then destroyed Japan as retaliation for this fire hose enema.
The end.