Being hungover causes people to make decisions based upon how they feel at the time, which is normally nausea, a headache, lethargy and a general feeling of impending doom.
Alcohol stops the body making the hormone that allows the body to absorb water. When you consume alcohol, everything you drink goes straight to the bladder. This leads to increased urination and dehydration.
The net result is you wake up exhausted, nauseous and with a thumping headache. It may be self inflicted, but it's still real, it still hurts and it's a problem. Someone needs to help the drunk fellas be responsible. That someone is gonna be me.