Credit to Benchem for coming up with this!
If you are suicide boosting for the Seriously achievement you can save yourself a weapon boosting session with this method. Please look at the details of suicide boosting in the achievement guides for Seriously. This is not a forum on what method is best for boosting Seriously. If you prefer suicide boosting this method will help you.
Make sure you are suicide boosting on the War Machine map.
Before the session starts ask to be the person getting shot by the torque bow. Make sure to explain what you are doing to the person using the torque bow first. While the effort is minimal on their part, not being on the same page is going to cause chaos.
Have your pistol selected. Stand a few paces apart from each other. Going to the same place every time makes this even easier. The person using the torque bow needs to aim at you and as soon as they start charging the torque bow shoot them IN THE HEAD until they die, about 5 shots should do the trick. When they die, the torque shot will release and hit you. They get their kill, you get a pistol/headshot kill.
Again, make sure the person using the torque bow is aiming at you and holds down the trigger without releasing it. Then start shooting their head.
The one caveat to this method is that you must finish before at least one of the grenade taggers. It should go without saying that you must both take the fastest path to the torque bow, no screwing around. Otherwise, the round will end before the person using the torque bow gets credit for their kill. Once you have it down, this shouldn't be a problem.
Anyone who has boosted Seriously with the suicide method knows that occasionally the torque bow is fickle. I did this with someone I'd been boosting with awhile so when the occasional mistake happened no one was blowing up about losing a kill. If it takes you more than 100 tries, well, you're in Seriously for 10,000+ so what's the rush? This achievement will pop up in one 2 hour suicide session or less.
Again, mistakes happen and this might take 1-3 rounds to perfect. Over the course of 10,000+ kills this will save you an hour or more and as any of the Seriously boosters know, every hour counts!