gifcam!

_fbp Cookie:

curl -X POST \
  -F 'data=[
       {
         "event_name": "CustomEventStanEvening",
         "event_time": 1781105818,
         "user_data": {
           "fbp": "" 
         }
       }
     ]' \
  -F 'custom_data=[
       {
            "value": 1781105818,
            "fart": "smelly"
       }
     ]' \
  -F 'test_event_code="TEST68733"' \
  -F 'access_token=EAAmZCmECZCKcIBAM6d2EX9JFWyNzKP9DZAmQYSLsFno8QScsCZA8MrRKa5XknfF0OWkelTqZAwIAjQp09TVw0o6qjUWZBP05e5Wk8L2GgEEWZC5ADVEu8MuHkFMEZBjBNMc0qq6POreqaFur0O9QwZBvELbhTMwdSCZAvB89y84ASDMIEe59SyOqdE' \
  https://graph.facebook.com/v8.0/414395756196031/events        

Result:

{"error":{"message":"Invalid parameter","type":"OAuthException","code":100,"error_subcode":2804050,"is_transient":false,"error_user_title":"You haven't added sufficient customer information parameter data for this event","error_user_msg":"This event has no customer information parameters, or it has a combination of customer information parameters that is so broad that it is unlikely to be effective for matching. To fix this, see best practices for parameters at developers.facebook.com\/docs\/marketing-api\/conversions-api\/best-practices\/#req-rec-params","fbtrace_id":"Ah9lknGKhvlZJ2rw8Xge9Ep"}}