I've found no other forum or precedent on these and would like to implement some consistency.
1) dj-->disc_jockey and dj (character) simply prefixed char to avoid the alias
Searching dj gives both disc_jockey posts and posts with characters named dj
2) ammo-->ammunition
I'm seeing posts with both and ammo is just short for ammunition
3) Vehicles (automobiles) This last one is messy to organize
I don't think tagging every specific make and model car is necessary and it's just starting nit-pick fights, maybe we can just tag as follows:
-car
-truck
-van
-bus
-sport/luxury (if it's even needed but I doubt)
-motorcycle
-atv (also probably not needed; only one image)
-tank
-apc? Not sure what to do with this one. Maybe it should be alias to one of the others, probably truck or tank
All these are the most common terms and should be implicated under vehicle, any more and that's just silly unless case exempts.
Updated by Blaziken