Green’s Dictionary of Slang

slobber n.

1. [mid-18C] porter.

2. [late 19C–1920s] nonsensical, sentimental chatter; gushing speech or writing [slobber v. (3)].

3. in attrib. use of sense 1.

4. [late 19C–1950s] a kiss [the swapping of spittle].

In compounds

slobber-chops (n.) (also slabber-chops, slobber-puss) [chops n.1 (1); modern use seems primarily for naming a pet]

[mid-17C+] a large-jowled person, a term of ridicule; 1639 use seems to suggest a stupid peasant.

In phrases

sling a slobber (v.)

[late 19C] to throw a kiss, to kiss.