삐끗 is an adverb describing the following situations: 1. two things going out of alignment (창문이 칭틀에서 삐끗 어긋났다 - The window is out of line with the frame). 2. an arm, leg, or some other part spraining (팔을 삐끗 삐었다 - I forced my arm the wrong way and sprained it). 3. something going wrong in general (여기선 발 한번 삐끗하면 낭떠러지다 - Here, one wrong step and you fall all the way).

it usually goes like "삐끗하다" which means you had a little injury in your body joints such as wrist, knee, etc. You can also say you 삐끗 your back when you hurt your back.