these add ons are often more expensive than you want them to be but I still do it
  1. avocado
    sometimes this can really enhance the dish
  2. malt (in milk shakes)
    usually like 10% of the base price and it makes shakes so much better
  3. additional sides
    usually at bbq places the sides are so good and there's too many to choose from and no one wants to share
  4. fried egg
    I hate that I can make this at home (cooked to perfection btw) but it really makes everything better
  5. peanut sauce
    sometimes restaurants charge for this, I think very highly of this sauce and I think you should too
  6. smoked salmon
    bagels with lox are often 3-4 times the price of a normal bagel with cream cheese but they're really good so idk is it worth it? I still can't tell