stumblebum (n.)

c. 1300, "to trip or miss one's footing" (physically or morally), probably from a Scandinavian source (compare dialectal Norwegian stumla, Swedish stambla "to stumble"), probably from a variant of the Proto-Germanic base *stam-, source of Old English stamerian "to stammer," German stumm, Dutch stom "dumb, silent." Possibly influenced in form by stumpen "to stumble," but the -b- may be purely euphonious. Meaning "to come (upon) by chance" is attested from 1550s. Related: Stumbled; stumbling. Stumbling-block first recorded 1526 (Tindale), used in Romans xiv.13, where usually it translates Greek skandalon.

"dissolute loafer, tramp," 1864, American English, from bummer (q.v.) "loafer, idle person" (1855), which is probably from German. Bum first appears in a German-American context, and bummer was popular during the American Civil War in the slang of the North's army (which had as many as 216,000 German immigrants in the ranks). There may also be influence or merging with bum (n.1) "buttocks," which was applied insultingly to persons from 1530s and is in Jamieson's 1825 Scottish dictionary. Bum's rush "forcible ejection" is recorded by 1910.