If your part time job pays badly, you might describe your income as piddling, or insignificant.
Why does English have so many words for suggesting that something is contemptibly small? The adjective piddling is a favorite choice when sums of money are concerned; a more dignified, but no less contemptuous word, is paltry. Piddling comes from piddle, which has changed in meaning over the years — in the early 1600's it meant "pick at one's food," while by the late 1700's it meant "to urinate."