drunk / drunken
The past participle of drink versus the attributive adjective drunken.
Drunk is the past participle of drink: he had drunk two beers; he was drunk. As a past participle, drunk also modifies a noun: a drunk driver. Drunken is a separate attributive adjective, used before a noun for habit or for behavior: a drunken boast. After a linking verb, use drunk. Before a noun, use drunken when you mean habit or behavior; use drunk when you mean a current state.
Examples
Use He was drunk. (predicative)
Use a drunk driver (past participle before the noun; current state)
Use a drunken boast (attributive adjective; the behavior)
Avoid a drunk boast (use drunken for the behavior)