You were just walking past a shop, you were a alcoholic so you were pretty drunk, you kept walking until a pig mask put a needle in you they made you fall asleep,

A couple hours later you woke up in a chair attached to bombs and then you see Jigsaw(A.k.a John Kramer)

John:"I want to play a game, you have 60 seconds to remove those bombs before you explode..use those knifes to chop your arms off and get the key to escape..times ticking.."