The 'Civillian Warthog, also known as a Pimphog but more commonly as the Golden Warthog is a yellow version of the UNSC'S Warthog with no 50.cal.
Don't go ahead and think that it's a total breakdown, it has a better paintjob and silver wheels of pwn which leaves burning flames in it's tracks (Legendary edition only). The turret from the UNSC's Warthog is replaced with another wheel which someone can use as a seat, this also makes it lighter and faster.
So yeah, it's basically a better Warthog with no guns, however, Gangsters enjoy customizing their vehicle's paint, performance and looks, so one day, one guy put a turret on his Pimphog! He was arrested but he just blew away the cops with the gun before they handcuffed him.
Bungie put billboards on the Halo 2 E3 demo, the campaign level Metropolis and the maps Headlong, Turf, Terminal and District which advertised the Golden Warthog, when they tried to unlock it so they could drive it. They emailed Bungie Studios, asking them to give away the secrets, the Bungie lord Jason Jones responded with
"The only way to get it is to get banned"
So then the retards decided to be dicks, perverts and privacy invaders, only to get banned. When they did get banned by Bungie, nothing happened, so those noobs went into their caves to play Call of Duty. A smart person figured out how to mod, so he took the turret out of the Warthog, made it gold and played on Matchmaking, Bungie saw this and banned the dude.
Using his mega brain, he realized what Bungie meant. The only way to get it is to mod, and modding leads to a ban.