This page is not a userbox. It simply displays its first parameter if it is Christmas Day, and its second if it is not.
In the example at User:GKFX/Userboxes, the code to display the template is {{User:GKFX/Userboxes/XmasSwitch|Yes|No}}
| Code | Produces |
|---|---|
{{User:GKFX/Userboxes/XmasSwitch|Yes|No}} | No |
{{User:GKFX/Userboxes/XmasSwitch|Yes|}} | |
{{User:GKFX/Userboxes/XmasSwitch||No}} | No |