The Sandvich is usually used as a portalble Medkit as it heals the Heavy's health to its maximum, however using it is risky, as it makes a lot of noise, alerting others to your presence. Once eaten, it cannot be used for another ten seconds, leaving you vulnerable to a Spy's backstab or a Sniper's bullet.
When Alt-Fire'd, (MOUSE2 by default) the Heavy will drop the Sandvich, which stays on the ground and acts as a medium-sized medkit, healing 50% of the user who picks it up's max health. However, when you are killed while holding the Sandvich, enemies can heal from it.
The Sandvich heals 300 health over the course of 4.2 seconds, and heals 75 health a second. This can outdo most damage done bye certain classes such as the scouts bats.
1. Deploy the Sandvich in a hostile zone near a group of wounded teammates if no Medics are available.
2. Find a safe area to eat the Sandvich, where you can be safe for at least four seconds.
3. Remember that when dropped, the Sandvich will heal your teammates and your enemies.
4. Perform a quick Spy check (sweep the minigun all around you) before you eat the Sandvich. This ensures that you will be able to eat your lunch in peace.
Of course, you can also do this method to conserve ammo.
1. Look around for enemies
2. Put your back to a corner3. Eat sandvich, as you can outheal all of the spy's damage output save for a backstab which can't be.