Green’s Dictionary of Slang

(US campus) to make a great deal of apparent effort, without any concrete accomplishment.

1896		W.C. Gore Student Sl. in Cohen (1997) 3: june around To be busy but not accomplish anything. ‘I have been juning around all day and haven’t a thing done.’ (Cf. junin’, running fast. An onomatopoetic word, from the humming noise made by june-bug).
1903		A. Adams Log of a Cowboy 228: To june a herd of cattle across in this manner would have been shameful.
1936		R.F. Adams Cowboy Lingo 216: A restless person was said to be ‘junin’ around’.