Arms with excessive cellulose or fat hanging from underneath the bicep. The fat is flabby and flaps like an uncooked tortilla. Expression possibly originating from from South Texas (e.g., McAllen, TX) with respect to large women grinding out tortillas in restaurants.
Dude, Sandra's got some awful tortilla arms. Maybe she could use them as a parachute like a flying squirrel.
Tom, as your wingman, I cannot allow you to go home with a woman with tortilla arms and a beer gut.