Add products automatically when user clicks buy

Is there any way to add the product the customer wants automatically from the momment they click on buy under the product itself rather than filling in themselfs? if we can talk about that to details on emial too i will be glad.thanks for your service.

I'm afraid that is not possible. However, if you like, you can set all the products to be pre-selected by default then user can just uncheck them if they don't want to include the items.