I couldn't find begi (or pegi - p and b are often interchangeable when transliterating from Korean) - but I hope this helps.
Could this be 빼기 -> bbegi? I've only taken a week of hapkido so far, but when my instructor says 빼기 he is refering to getting loose from a grab. I have been taught three types of 손빼기 so far. Bbegi means to subtract, or get loose from something.