You have to use special earrings for this. They have to be sharp/pointed at the end of the post,and they must be good quality so they don't snap or break when piercing
I hate to sound offensive or snippy but it really is unsanitary. When a piercing gun is used unless it is fully sanitized with alcohol microscopic blood particles spray onto the gun and can spread bacteria etc. That's why its considered more sanitary to use the hollow needle method. So by all means auction it but clean it up with rubbing alcohol :-)