This is a very recent game that has started and it's only a session or so in... but already it is proving to be highly interesting. Just keep in mind that all the players are human (no Chaos space marines).
The Khornite former guardsmen manages to get his mates together (the other players who are members of his squad) and tells them what he wants to do in order to earn the attention of the Chaos Gods. "I want to create a weapon... and have it blessed by Khorne personally."... as in in person. He plans to somehow travel into the warp realm of the Blood God himself, borrow one of the demon forges that are there long enough to create a weapon, then make the pilgrimage to the Skull Throne itself and ask the Blood God in person to bless it with his power; His logic being that if they can somehow survive the journey and make it that far, Khorne would be impressed by the sheer size of their balls and the amount of blood that they would have had to spill to get that far.
While at first the other members of the party are... skeptical of this plan, the main Khornite starts to win them around to it with the promise that 'We could burn a thousand worlds and offer up untold trillions of souls to the Chaos Gods and they won't bat an eye because countless other **** have already done it before us but I can promise you that the gods themselves will have to acknowledge us if we can stand before the Skull Throne itself and look Mighty Khorne in the eye... and they will remember us because no one has ever done it before and possibly never will again.'
So the party is currently making plans to gather a Black Crusade together. Not to invade the Imperium, but to launch an invasion of Khorne's personal realm in order to earn his blessing in person at the most holy of sites to a Khornite. They aren't even planning to try and hog the blessing for themselves; As far as they are concerned, if anyone survives to make it to the Skull Throne itself after fighting through the Blood God's realm, they earned their place there and any reward that Khorne deems fit to give them. Worst case and they fail... well, they figure they might still get Khorne's favor for trying if they fight hard enough. After all, no one has ever launched a Black Crusade into his realm before...