To become old or stale; to lose freshness or flavor. Used colloquially to indicate something has aged or deteriorated.
買い置きしていたお茶が長く置いておいてひねってしまった。
The tea I had stored for a long time has gone stale.
古い米はひねると炊いても味が落ちる。
Old rice loses flavor even when cooked if it has gone stale.
To be too grown-up for one's age; to be precocious. Often used about a person's manner or thinking.
小学生なのに彼女はとても落ち着いていて、少しひねっているところがある。
Although she's an elementary-school student, she's very composed and somewhat precocious.
その子は話し方がひねっていて、同年代より大人っぽく聞こえる。
That child speaks in a precocious way and sounds more grown-up than others his age.
To become twisted, warped, or perverse (in personality or form). A colloquial sense similar to 'to become perverse' or 'to turn sour'.
最近彼は周囲に反抗的で、少しずつ性格がひねってきたようだ。
Lately he's been rebellious; it seems his personality has become a bit twisted.
古い木材は乾燥してひねることがあり、使う前に注意が必要だ。
Old wood can warp as it dries, so you should check it before using it.