You can use the downloadable menu in the right column of this webpage and phone and place a "to go" or "takeout" order. It may be difficult to get through by phone at the busiest times.
Groups can call in their orders ahead or simply show up.
In person, one almost never has to wait more than ten minutes to place their order.
There is one line for just ice cream and another line that is for other food (but you can order ice cream there as well).