way down the list of senses for 'crib' are these:

7. colloq. To pilfer, purloin, steal; to appropriate furtively (a small part of anything). [Prob. orig. Thieves' slang, connected with sense 7 of the n.]
1748 Dyche Dict., Crib, to withhold, keep back, pinch, or thieve a part out of money given to lay out for necessaries. 1772 Foote Nabob 1. Wks. 1799 II. 298 A brace of birds and a hare, that I cribbed this morning out of a basket of game. 1795 Hull Advertiser 31 Oct. 4/2 We would never have cribb'd your papers. 1825 Cobbett Rur. Rides 28 Bits of ground cribbed+at different times from the forest. 1862 Mrs. H. Wood Mrs. Hallib. ii. xii. 204 We crib the time from play-hours. 1884 Times (Weekly Ed.) 17 Oct. 2/3 How many Tory seats he can crib there.
absol. 1760 C. Johnston Chrysal (1822) I. 174 Cribbing from the till. a1839 Praed Poems (1864) II. 8 Both of old were known to crib, And both were very apt to fib!

8. colloq. To take or copy (a passage, a piece of translation, etc.) without acknowledgement, and use as one's own; to plagiarize.
1778 J. Home Alfred Prol., And crib the prologue from the bill of fare. 1844 J. T. J. Hewlett Parsons & W. xlvii, Flogged for cribbing another boy's verses. 1862 Sala Accepted Addr. 168 Antiquarian anecdotes (cribbed from Hone, etc.).
absol. 1862 Shirley Nugæ Crit. vi. 266, I rather suspect that Homer+cribbed without+compunction from every old ballad that came in his way. 1892 Pall Mall G. 19 Oct. 3/1 At school+it was dishonourable to ‘crib’ because it would be to unfairly injure+others. [OED]

{sense 7 of the noun 'crib' is a small basket or bag -- bag being another colloquial term for steal}