I once ran a game where the characters were working for the mob, and didn't like it.
The mob didn't like them either, but was using them to do dirty work that they couldn't get their hands dirty with- especially stuff involving other crime families and acts of terrorism.
Anyway, one of the jobs, the mob guys ended up double-crossing the runners. Trying to kill two birds with one stone. The runners didn't like this, and knew who hired them, so they went and confronted the mob boss (who I had named 'Mister Bigglesworth' after the cat from Austin Powers).
The mob boss said
"What? You don't like it? File a complaint." He laughed, a deep belly laugh, thinking that no one would be stupid enough to try anything with all his goons around, and even if they did, his boys would hose the place down with lead until only a smear of runner scum remained.
Ruski, one of my players, activated wired reflexes, whipped out a pistol, and burned a bunch of karma to go first. He fired, point-blank, into Mister Bigglesworth's head, in his words 'turning it into a canoe.'
Mister Bigglesworth is dead, everyone else gets to act. The goons fire (their readied action, in case anyone did anything stupid). One of the other runners, the street sam, is wearing armor, and best able to resist automatic gunfire. The other ones, not so much. The street sam (Ray, I think his name was) dragged his two best friends- the one dumb enough to shoot a mobster in the face in full view of his henchmen, and the other one close enough for him to grab, and makes a run for it.
The rigger is outside, and ready to go (they weren't complete morons). The goons are still shooting- Ruski's character is bleeding out, the other guy is bleeding out, and Ray the Sam is taking a lot of damage. He throws Ruski's corpse into the van, sprinting at 50kph, misses when he tries to throw the other guy in, and decides to make one last attempt to throw in the 'other guy' before jumping in himself (his other choice was to drop the other guy, and save himself).
Makes the throw with the other guy, takes damage and goes down before his next initiative pass. The rigger and the 'other guy' were the only ones to survive. Saddest part was that the 'other guy' was a jerk- he fired at gangers
through the windows of the rigger's car, refused to take part in tense negotiations because they were 'dangerous' leaving the group rigger to try and grab a briefcase when another Johnson tried to double-cross them; and
that is the guy who survived.
In our group, a TPK (or mostly party kill) was the signal that it was someone else's turn to GM. Ruski had gone before me, I went, so the Jerk's player was the next GM, and he spent five or six session with his former character as Mister Johnson, blowing up and messing up everything the runners had done for the mob up until that point; before, of course, screwing over the runners himself, and leaving town with all the profits.
When it swung back around to my turn to GM again (a couple years later), the runners were hired to extract someone, and this same Jerk's security company happened to be in the same area, so they were paid extra to trash the place and steal any paydata they could find. Just for yuks, because most of the players were the same.

-kv