These are flak-jackets that soldiers wear to protect them from shrapnel. They are thick, heavy, hot and made of non-breathable material. Although they are useful in a war situation, they do nothing but dehydrate troops whilst training. The warm-hug is therefore also known as the dehydrater.
Learning to use the M203 grenade launcher wouldn't be so bad if I didn't have to wear my helmet and warm-hug.