Step 1:
If you want to make a life-size burger, just glue or tape 4 papers together to make one large Origami paper.
Prefold in half, then turn the paper.

Hungry!                          Oh no, the dog is taking them!!

Step 8:
Make a tube by inserting the part on the right under the edges on the left, see arrow.
Use glue or tape to hold the tube together, if necessary.

Step 6:
Squash-fold the edge, see arrows.

Step 13:
Press the tip flat between your fingers.

Step 12:
Glue/tape the loose parts to the model, see arrows as example.

Step 11:
Repeat step 9 about three more times, until the whole edge is folded downwards.

Step 10:
Press this part downwards too.

Step 9:
Press the edge downwards by folding over these lines.

Step 5:
Fold over these 3 lines.

Step 7:
Mountain-fold over these 2 lines.

Large Origami Hamburger Paper

Step 3:
Valley-fold over these 2 lines.

Step 2:
Valley-fold over these 2 lines.

Step 4:
Prefold over these 2 lines.

Step 14:
Repeat steps 9 to 11 at the bottom of the burger.
The edge at the bottom is folded completely downwards.

This is how the bottom of the hamburger should look.

Puppy dog eating a hamburger

In this video Joost Langeveld shows us how to fold the hamburger:

Hamburgers background pattern