If your girl doesn't know you are using, you can still go with her and give blood without it getting to a patient. I have given blood many times prior to my steroid use, and before they take your blood they give you 2 barcodes. One barcode says you allow them to use your blood, the second says you don't allow. Just put the second barcode on the proper place and you will go through the entire blood giving process but your blood won't be used. If your girl knows you are using tell her you can't give blood and save yourself the hassle.