No, you can’t get avocados on an In-n-Out burger. However, you can get spread on the side and store it in your secret refrigerated treasure trove at home for later.
Here I stacked 3 burgers with 3 slices of cheese (3x3), added a generous amount of In-n-Out spread, topped that with the freshest of tomatoes from my garden, capped it off with some avocados because #california.
Keep your lettuce. This was D-freakin-VINE.