When in the Mombassa streets at night time, simply press X to activate your VISR. Then its just 5 kills for a 5g achievement!!!
Unlocking this achievement and then launching Halo Waypoint will unlock an ODST Hoodie for your avatar as an award - see here for more information: http://www.xboxresource.com/forum/viewtopic.php?f=134&t=...
Thanks to x2i4eva