How do you get the code on pandas bigger adventure

It depends which box you mean. The crate in the trench area, or the box in Leonardo Di Vinci's room.
The answer to the crate is different every game. (I've tried it myself) But all you have to do is get the shaver from Leonardo Di Vinci's bathroom, (to unlock it you change the hands on the clock to match were the drawn in white ones are) then you go to the trench area and you shave the mans face besides the locked crate. The number on his chin is the code to the crate.
The answer to the box in Leonardo Di Vinci's room is on the paper that is lying in the bathroom. The CAPITALIZED letters are the points on the compass that are on the top of the box.
Hope this helped! :D