Green’s Dictionary of Slang

pissed adj.1

also peed
[piss n. (1)]

[20C+] drunk; thus half-pissed, tipsy.

In phrases

pissed as... (adj.)

[20C+] in combs. with a n., very drunk; for expressions other than those listed below see drunk as (a)... adj.

...a newt [1950s+]
...a parrot [1970s+] (Aus.)
...a rat [1980s+]
...a sparrow [1980s] (Aus.)
pissed to... (adj.)

[1960s+] in combs. with a n., very drunk.

...the ears [1960s+]
...the eyeballs [1980s+] (Aus.)