Coworker won’t take hint I don’t want to go out with her after 2 years

i’ve had this coworker for about two years now. She has been asking me to go out for drinks ever since she trained me. I’ve dropped every hint and used every excuse in the book for two years. Now she’s resorted to mentioning it at the beginning of every shift and the end of every shift. She even texted me about yesterday out of no where. I serioisly don’t know what to do, my friends said be straight up but that’s just feels so mean to me. I’ve been dry too. Nothing works. It’s been two years why isn’t she getting my hints ?