Bub
mid 19th century: from earlier bubby (perhaps a child's form of brother), or from German Bube ‘boy’.
wiktionary
Probably imitative of the sound of drinking.
Contraction of bubby.
Either a corruption of brother, a modification of bud, or a borrowing from Pennsylvania German Bub or Southern German Bub (as was spoken in various communities in America before the early 20th century), ultimately thought to be derived from Proto-Germanic *bō-(“close [male] relation”) and thus cognate to English boy and babe.
bub (plural bubs)
Shortened from bubble and bubbly.
etymonline
bub (n.)
"a woman's breast," 1860, short for bubby.
bub (n.1)
also bubby, familiar address for males, 1839, perhaps a variation of bud "a little boy" (1848), American English colloquial; perhaps from German bube "boy." But sometimes, along with bud, assumed to be a corruption of brother (compare buddy, bubba).
bub (n.2)
"strong drink of any kind," especially malt liquor, 1670s, perhaps imitative of the sound of drinking.
