Here is the full list of all 45 BDSM: Big Drunk Satanic Massacre achievements.
The ending: LOU marries Angelica
Solve the game, any ending
The ending: LOU agrees to Big Wac's proposal
Complete all quests
Complete Back to School quest
Complete "Steak from Hell" quest
Complete "Love is Blind" quest
Complete the quest with Mort's girlfriend
Complete the Interview quest
Complete "Save our bones" quest
Complete Soldier of Fate the Infector quest
Defeat Behemoth
Defeat Big Wac
Defeat Black Overlord
Defeat El Roico
Defeat Nerdomancer
Rise from the dead
Summon 20 imps with magic
Use rage 20 times
Don't use bottles during one level
Open 20 doors
Spend 3 hours fighting
Buy 5 abilities in store
Collect 100.000 coins
Spend 100 grand
Max out the ammo bar
Max out the bottle bar
Max out your HP bar
Blow up 50 barrels
Blow up 20 vending machines
Defeat 500 enemies
Defeat 15 enemies in 3 seconds
Defeat 100 burgers
Defeat 30 tourists
Defeat 100 enemies with AK 47
Blow up 5 enemies with one grenade (AK 47 alt attack)
Defeat 10 enemies by blasting a barrel
Defeat 100 enemies with a bazooka shot
Defeat 100 enemies with BFG
Defeat 30 enemies with dash
Defeat 30 enemies with minions
Defeat 50 enemies with a revolver
Defeat 50 enemies with a shotgun
Defeat 100 enemies with Soulgun
Complete Metal Gear Pony quest