can someone explain to me what i did in this? cuz im so confused..

You guessed right, you pushed yourself OoB with the box. You can only do that when you get a weird physics bug that makes your collision messed up. Normally when you drop a box on your head or throw a barrel at yourself it'll just bounce off. But rarely (when you load a map) Daniel and monsters can get "Slippery Physics".

There's a video of it happening with a grunt, back when I made that video I didn't know it could happen to Daniel's hitbox but the same principle applies.

thanks for the reply :P i thought it was quite strange that i just randomly got pushed through a wall lol