|“||Ahh, that hunk of rock was gonna blow up anyway||”|
Kaiba-5 is some planet or some moon of a planet, presumably in a system named Kaiba or orbiting a planet named Kaiba. It may or may not have blown up, but it can definitely screw the rules, 'cause its got money.
Whatever it is, it's a testament to one simple fact: Ironhide is waaaay too trigger happy.
Transformers: The Game
Ironhide presumably damaged it, and in a way that was almost certainly violent. When Optimus Prime requested that he rescue Jazz, he warned Ironhide not to make another incident "like Kaiba-5". Ironhide defended his actions to Optimus by saying it was going to blow up anyways.