Dorothy took the chance of the moment and used her nails to cut her own finger but instead was greeted with the fact that shes dead and has no blood so now she just has a hole in her finger
She stuck the needle in and looked in pain the she took and it out and blood came out, she grabbed a tissue and wiped the blood off and put a band-aid over.
Dorothy put her bottle back in her bag and searched up “how to faint” so she can act like shes freaked out by blood (shes just putting herself deeper and deeper into trouble)