In 40th Day, you can walk up to enemies, and press the grenade button. Your character will wrap their arm around thier neck and take them hostage. This can help in 2 ways.
- A makeshift meat-shield
- A way to save civilians when they are hostages.
The latter works by grabbing the senior officer. Often the only one wearing a helmet. His grunts will surrender and put their hand up. They will then get on their knee's. After that, your partner can either kill them or tie them up. You can do the same with your hostage.