Green’s Dictionary of Slang

shitfaced adj.

also shitface, shitty
[fig. uses of shit n. (1a) + SE faced]
(orig. US)

1. [1930s+] stupid, ignorant.

2. [1960s+] very drunk.

3. [1970s] under the influence of cannabis; occas. other drugs .

4. [1970s+] a general intensifier: total, complete.

5. depressed.