Acting drugged

[Spearmint Rhino]

Arguably a bit easier than acting drunk, because the wide range of drugs to choose from, and the even wider range of possible reactions to them, mean that you can get away with pretty much anything.

A couple of brilliant examples, anyway:

Johnny Depp in Fear And Loathing In Las Vegas

Brad Pitt in True Romance

[Stumpy Pepys]

Acting drugged

John Travolta in Pulp Fiction.

[Ginger Yellow]

Acting drugged

Jeff Bridges in Lebowski.

[manandvans]

Acting drugged

Presuming Ed in Withnail & I.

[erwin]

Acting drugged

John Hurt in Midnight Express.

[Lucia Lanigan]

Acting drugged

The thir-fucking-teen year old model who was actually 19 in Nathan Barley.

[jason voorhees]

Acting drugged

The thing about Fear and Loathing in Las Vegas was that it was the first film I saw that actually captured exactly what it's like to be high. It's like they took acid and smoked weed for a week or two, and took as many production notes as they could (the light shines kind of orangey-yellowey, people move sort of choppy and seem to jump cut when walking, the sound is tinny and there's some weird buzzing white noise in the ear, there's a faint carnival music playing - but just quiet enough that you can't discern what tune or instrument is playing, etc.)

Julianne "Amber Waves" Moore and Heather "Rollergirl" Graham must be the Citizen Kane of coke binge scenes.