Any advice or tips on how to gain 20 pounds in 2 days?

Hi, I'm 16, and I'm trying to put on weight by Wednesday because I signed up for a blood donation at my high school. One of the requirements is that you need to be at least 110 pounds (49.8kg) I weigh about 90 pounds (40 kg). I would like to donate my blood, but I am afraid I am unable to do so because I am underweight. I am currently trying to eat foods high in iron, with a lot of protein and also eat a larger portion of food. Any tips or advice?

Any advice or tips on how to gain 20 pounds in 2 days?
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