The erection won’t do you much good as you try to avoid going into respiratory arrest:
Symptoms may appear within 10 to 20 minutes after the bite, and death within two to six hours, where severe pain radiates to the rest of the limb, systemic effects include tachycardia, increased blood pressure, vertigo, fever, sweating, visual disturbances, nausea, vomiting, difficulty breathing and paralysis.
The good news is you get a four hour erection.
The bad news is that you die within two hours.
Priapism isnt something you want. Eventually the blood will clot in your penis and no new blood can flow in, causing the cells in your penis to die from lack of oxygenated blood eventually leading to amputation. Better make those 4 hours count
You don’t want that spider bite: https://youtu.be/JN0VtHez9xI (12:35 SmarterEveryDay video)