Green’s Dictionary of Slang

clabber n.

1. (US) semen.

in Randolph & Legman ‘Unprintable’ Ozark Folksongs (1992) I 204: The first time i saw her she was floating downstream, / With a belly full of clabber and a cunt full of cream.

2. see clobber n. (1)

3. see bonny-clapper n.