The Core Reason
Alcohol causes muscles to relax more, including those found in your throat.
As your muscles in your throat surrounding your upper airway over relax, they push against you airway reducing the size and restricting airflow.
Air from breathing as you sleep still needs to rush in and out, but now through a much narrower air passage.
The air speeds up and soft tissues found in your throat and mouth vibrates and causes the sound that you hate as snoring.
Other Possible Contributing Factors
As you sleep, your central respiratory system actually reduces your normal ability to take air into your body.
Obviously, this coupled with the overly muscle relaxation causing restricted airways, makes the snoring even worse.
The greater the extent of restricted airways and respiratory difficulty, the louder the snoring tends to be.
There is a growing trend of more and more middle aged people suffering from some form alcohol induced allergy. Under normal circumstances, the allergy symptoms are unnoticed. However, the underlying allergy does often lead to an inflamed respiratory system further increasing your inability to pass sufficient air in and out as you sleep.
Some Quick Fixes For That Drunk Induced Snoring Night
Poke and push the snorer onto their side, which causes the airway to get a little more space causing less vibrating tissue and, therefore, noise.
Stick in some special snore barrier earplugs.
Sleep in another room.
Stop them drinking so much.
Get to bed well before they get to bed and try and get some undisturbed sleep.