by 1973, perhaps with suggestions of dangle and berry. Attested from late 19c. through 1930s as a humorous-sounding surname in comedic writing.
Entries linking to dingleberry
dangle v.
1590s, intransitive, "hang loosely, be suspended so as to sway in the wind," probably from Scandinavian (compare Danish dangle, Swedish dangla "to swing about," Norwegian dangla), perhaps via North Frisian dangeln. Transitive sense of "carry suspended so as to swing or sway" is from 1610s. Related: Dangled; dangling.
berry n.
Old English berie "berry, grape," from Proto-Germanic *basjom (source also of Old Norse ber, Middle Dutch bere, German Beere "berry;" Old Saxon winberi, Gothic weinabasi "grape"), which is of unknown origin. This and apple are the only native fruit names.