It depends what you mean by discreet. Because you don't want to give your real name, or you don't want the transaction to show on your statement?
A lot of providers ask a deposit on a gift card, or sent on Throne. In both options you wouldn't have to divulge your real name, but your provider of choice could ask for a photo of your ID.
Others can accept a photo of the back and front of a physical gift card, but it's an option that's not offered often.
I am sure others will come up with other options that I don't think of right now.
Note that you can only choose among the options the provider gives you, you can't decide by yourself how and how much to send. If none work for you, it's simply best to respectfully decline and move on.