"persist through adversity," 1969, usually with there; see hang (v.) + in (adv.).
Entries linking to hang in
hang v.
a fusion of Old English hon "suspend" (transitive, VII strong verb; past tense heng, past participle hangen), and Old English hangian "be suspended" (intransitive, weak, past tense hangode); also probably influenced by Old Norse hengja "suspend," and hanga "be suspended." All from Proto-Germanic *hanhan (transitive), *hanganan (intransitive) "to hang" (source also of Old Frisian hangia, Dutch hangen, German hängen), from PIE *konk- "to hang" (source also of Gothic hahan, Hittite gang- "to hang," Sanskrit sankate "wavers," Latin cunctari "to delay;" see also second element in Stonehenge).
As a method of execution, in late Old English (but originally specifically of crucifixion). Meaning "to come to a standstill" (especially in hung jury) is from 1848, American English. Hung emerged as past participle 16c. in northern England dialect, and hanged endured only in legal language (which tends to be conservative) in reference to capital punishment and in metaphors extended from it (I'll be hanged).
Teen slang sense of "spend time" first recorded 1951; hang around "idle, loiter" is from 1828, American English; also compare hang out. To hang back "be reluctant to proceed" is from 1580s; phrase hang an arse "hesitate, hold back" is from 1590s. Verbal phrase hang fire (1781) originally was used of guns that were slow in communicating the fire through the vent to the charge. To let it all hang out "be relaxed and uninhibited" is from 1967.
in adv., prep.
a Middle English merger of Old English in (prep.) "in, into, upon, on, at, among; about, during;" and Old English inne (adv.) "within, inside," from Proto-Germanic *in (source also of Old Frisian, Dutch, German, Gothic in, Old Norse i), from PIE root *en "in." The simpler form took on both senses in Middle English.
Sense distinction between in and on is from later Middle English, and nuances in use of in and at still distinguish British and American English (in school/at school). Sometimes in Middle English shortened to i.
The noun sense of "influence, access (to power or authorities)," as in have an in with, is first recorded 1929 in American English. to be in for it "certain to meet with something unpleasant" is from 1690s. To be in with "on friendly terms with" is from 1670s. Ins and outs "intricacies, complications of an action or course" is from 1660s. In-and-out (n.) "copulation" is attested from 1610s.