As much as can be carried or worn on one's shoulder.
As he walks down the hall to meet a group of businessmen, this corporate secret service uses code ling and the phones' two-way radio feature to head off potential snafus, such as toilet paper trailing from his wing tips and "snow on the mountains" (a shoulderful of dandruff), while he's unaware in a Mr. Magoo sort of way of the action surrounding him.1998, Brandweek - Volume 39, Issues 9-17:
Before I could give him a brisk lecture about how making an effort for an hour could help his career no end, a large man with two shouldersful of bags hoved into view.2008, Hester Browne, The Little Lady Agency in the Big Apple, page 214:
4 more examples
He could get a shoulderful of one-by-sixes off the lumber pile and carry them up to the cabin site.2015, David Margolis, Change Partners:
She hefted two small packages, sighed with disgust, and shifted the lot in her arms, finding room for another shoulderful.2018, Steven Barnes, Streetlethal:
With a shoulderful of medals, he returns home after nine years, ready to put down his guns and find some kind of normalcy.1989, William Edward Burghardt Du Bois, Crisis, page 12:
Don't travel on it then, she was told in the boarding house, or you'll find yourself jammed in, breathing shoulderfuls of damp tweed.2012, Frances Osborne, Park Lane:
2
An amount that reaches as high as the shoulder.
Sacramento River flowing circuitously below high crimson banks and a splendid view of America's only volcano (whose last eruption occurred as recently as 1914), rising steeply out of the level valley and hoisting a shoulderful of superb colors against the sky.1939, New Catholic World - Volume 148, page 416:
3
As much as a metaphoric shoulder can handle; a personal burden.
Gent who was with her had a shoulderful of chips, for no apparent reason.1958, Stewart Sterling, Dead to the World, page 52:
The new regime allowed for an incredible latitude of flexibility but also an equal shoulderful of additional responsibility.2001, Bart Wheeler, Barn-Like Rome, page 142:
shoulderful
adj
Etymology From shoulder + -ful.
1
Filled as far as the shoulder (of a container)
2
Having large, muscular shoulders.
Small, dogged, shoulderful, they come headed America-ward.1930, Lucy Lockwood Hazard, In Search of America, page 572:
Golden brown shoulders bulge out of that sleeveless shirt in a way that's almost profane, like just sitting there, being all burly and shoulderful in front of a group of teenagers seems somehow inappropriate.2016, Daniel Jose Older, Midnight Taxi Tango: