What should you ask for?
Ask the order taker whether chopped chilies can be added to your chosen burger. Specify the amount you want and confirm any charge. An available side pepper and a pepper cooked or chopped into food are different requests.
The reference site names this customization, but it does not provide primary documentation for the pepper variety. This guide therefore does not assert a universal cultivar or a guaranteed Scoville rating.
How does it compare with Animal Style?
Chilies are a separate ingredient request. The official Animal Style definition includes mustard-cooked beef, pickles, extra spread and grilled onions; chilies are not part of that published definition.
Keep a chilies request distinct so the cashier does not need to infer it from the named burger preparation.
What about nutrition and allergens?
An exact calorie, sodium or heat value depends on the peppers and portion. No dedicated verified nutrition entry is available in this guide. Review the current allergen information and speak to staff about any dietary constraint.
For documented preparation choices, compare the Not So Secret Menu or browse the full in n out menu.