Green’s Dictionary of Slang

forward adj.

drunk.

1770		Gent.’s Mag. Dec. 559/2: To express the condition of an Honest Fellow [...] under the Effects of good Fellowship, it is said that he is [...] 35. Forward.
1786		F. Pilon He Would be a Soldier VI ii: ca.: Why, now I look at you, I think you are getting a little forward. [...] johns.: Zounds, Sir, I am not drunk.