Today I GM'ed a one shot using 3 Ork Freebooters (Driva, Mekboy, & Runtherd). I used pregens in Rank 2, and stayed away from complex talents.
The hook was they were part of an expedition going back to the Waaagh with the Big Red Button. Their ship was attacked, and they crash landed in an orcish shuttle on a human colony/maiden world. 'umies and panzies fightin everywhere.
As the only survivors, the goal was to take the big red button, find a spaceport, steal a ship, and boost into orbit where a waiting Ork starship would take them back to the Waaagh. Each Ork had a warbike. The runtherd had a sidecar for his squig and gretchen (and a dead 'umie who he kept ordering around).
The encounters were with human deserters who wanted to loot the xenos ship (who were arguing about this being some odd kind of Eldar craft, who says Orks are dumbest!) a Rhino full of PDF troops, an Eldar Warlock ambush, and at the spaceport, a fight with PDFs and an Ultramarine.
A good time was had by all. The 'umies got slaughtered, the panzies faded away after loosing 1/3 of their numbers. The Ultramarine was hard to kill, but I rolled terrible for him. He lost his chainsword early on, got hit hard by all three Orks, who then jumped back and tossed in a 'Sloding Squig that the hapless Gretchen caught. It blew up, got Orkish Fury, and the day was won for the greenskins. Although suffering from critical hits, they stormed the shuttle and took off.
The fun part as a GM was describing the world from an Ork's perspective. "There are two types of 'umies: Screemers and Fun 'umies. Da fun ones fight back. Da screamers (civilians) are gud because they scream when squished and den the Fun Ones show up."