The records about this elusive and hard-to-document Space Marine Chapter are reported to most likely, most easily be accessible by being drunk yourself. Imagine warp gate travel. The mental state reached to access this information can vary with the type of respective alcoholic beverages ingested, just like with warp travel.
Despite similarities (such as a love of fighting, drinking, and fighting drunk) the Drunk Marines have no relationships to Space Wolves, dwarves, or squats. These Marines are just one of the fellow factions that like to drink. Don't hate them for that simple fact. Consider the grimdark universe of W40k. Who would NOT drink, given the chance, no matter what race you are born to?
A mysterious /tg/ homebrew chapter (possibly a successor to the Space Wolves), the Drunk Marines Chapter specialize in the ancient art of confusing the enemy with sheer stupidity along with sometimes belching entire sentences, or bursting into a chanting student song for no apparent reason. The biggest threat to the drunk marines is the fact that most planets don't sate their thirst for booze (favorites of them all are mead, ale, rum, and whiskey). When a planet's alcohol reserves are bled dry, the Drunk Marines leave on one of their massive Barrel Ships to search for more booze to keep the party going. If the next planet is just a slight light year away and they slip into their more agitated and volatile state, the "hangover", the consequences could be dire and even an occasional stray Hive Fleet is not safe. The Drunk Marines, once in a hangover state, will rage (not quite as hard as the Angry marines however) and smash and bite whatever they can to get more booze. Sometimes the Drunk Marines drop from orbit to find the planet they so desperately desire for it's legendary alcohol is overrun with greenskins or worse, Chaos (who instinctively find drinking a pussy sport). The Drunk Marines, while slow, love operating machinery, even while drunk. They will go to whatever lengths they can in order to once again maintain their constant state of incoherence and happy-go-luckiness.
It is rumored that their Chapter Master used to be the elusive Tonius Starkonian.
One (two?) of their brethren were caught in a Warp storm whilst on a recon mission, and ended up dumped in 1960's America. They eventually became the RED and BLU team Demomen.
The Tale Of The Bard "Hey Korgan!," shouted a marine from across the oldland style bar.
There were stacks of kegs higher than any frail Imperial Sentinel stacked all around the room. The walls were illuminated with oldland style candle lights, instead of photons. All about the room marines were singing, dancing ancient and legendary jigs. Some were even passed out leaning into their barrel droughts fast asleep, content with the gallons upon gallons of ale they had consumed through the past few days. None could match the chapter master Korgan however. Ever since he had made planet fall in the first wave (to be the first to the drinks more than likely) he had never once stopped swigging from barrel after barrel of sweet borderland rum.
Korgan looked up from his drink to spy a Chaplain standing (barely) across the room with the book of liturgies in his left hand and his right hand safely guarding a fresh barrel. Korgan hefty his might barrel above his head and tapped it dry with the thirst of a man stranded in the desert and the strength of a bear.
"Aigh' Lad we will have us a good tune together we will!", Korgan hollered back as he shifted haphazardly across the birth of the great room.
Once he reached the Chaplain, and the new keg had been tapped and half way drained, the real singing began. They sang of legendary brews of planets long gone. Of fallen comrades who still wish to have fought on. But all the marines joined in in the ballad of the chapters song. When They sang of their founding protecting Terra very long ago. They sang of their brethren, even the angry and pretty ones. And when the alcohol had been drained, they hefted their bolters in their hands and staggered as best they could to their landing pad. Anxious to head to another planet, and another party.''