burdensome, pack horse, horse load, send by horse, trivial, worthless
駄 centers on a horse carrying a load, which extends to anything burdensome, trivial, or worthless—like cheap goods sent by pack horse.
駄 combines 馬 (horse) with 太, which likely contributes the sound 'da/ta' and may suggest a large or heavy load. The character originally referred to a pack horse or horse load.
A horse (馬) carrying a big (太) load looks burdensome and the goods seem cheap and trivial.
For ダ, imagine a tired pack horse going 'duh' under the heavy load: duh -> ダ, and the horse is burdened with worthless stuff.
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no good; not serving its purpose; useless; broken
futility; waste; uselessness; pointlessness; idleness
waste (of money, time, etc.); squandering; frittering away
geta; traditional Japanese wooden sandal
penny candy; cheap individually wrapped sweets
feeble joke; poor joke; corny joke; bad pun
entirely useless; completely worthless
poor; low-grade; trivial; insignificant; worthless
poor piece of work; rubbish; trash
whining (to get one's way); tantrum
poor piece of writing
visit for no reason; going on a fool's errand
unmanageable child; spoiled child (spoilt); spoiled brat
reward; recompense; tip
foolish tale; nonsense
mongrel; cur; mutt
chatter; idle talk
leather-soled sandals (geta)
Pacific needlefish (Strongylura anastomella)
packhorse; workhorse; hack