Here is the homebrew I now use 

Drunkenness takes place in 5 levels each level retains the effects of the previous:

1: Tipsy (1-2 drinks *) More aggressive, -1 to int and wis, +1 to strength

2: Intoxicated (3-4 drinks *) Disadvantage on all checks except strength, advantage to strength

3: Drunk (5-10 drinks *) Movement speed is halved, Disadvantage on all saves,

4: Very Drunk (10-20 drinks *) wis, int, and constitution checks automatically fail, inverse Darkvision effects

5: Alcoholic coma (20+ *) Knocked prone, Paralyzed

*Exact amounts of drinks may vary at the DM's discretion*

There are several gamelit books I have read where as the characters level up they have to buy stronger alcohol as their high constitutions prevent them from getting drunk.  The more powerful stuff is also more expensive.

Basically, think of "Dwarven Ale", that can get people drunk even if they are immune to Poison.   And of course, it would hit someone without immunity like a ton of bricks.

I use the poisoned condition for alcohol and drug intoxication and if usage persist, resort to Exhaustion rules.  It reflect well people becoming dysfunctional,  passing out from ethylic coma and even dying of overdose.

Do you also sometimes get double, triple or quadruple slapped when making these bad jokes? ^^

Quote from bobberuchi >>

You could get drunk by a whale, or would that just be swallowed?  There may need to be a big blender first. 

 

Depending on the level of drunk I go with disadvantage, triple disadvantage, or quad disadvantage. 

 Really hope none of your players have the lucky feat of your in for a bad time. Quad disadvantage? Welcome to quintople advantage. 

Quote from The_Leviathan_of_Levistus >>

There is no such thing as double, triple, or quad disadvantage. 

Poisoned/Drunk makes you have disadvantage on attack rolls and ability checks. 

This made me laugh far too loud on a train.