A person who thinks that he/ she is proficient at gaining the attention of attractive individuals in a social setting (wingman) however, their proficiency is questionable and is mocked openly by the previously mentioned attractive individuals.
"Wow, John is a real Wing dinger.." said with a tone of sarcastic disdain.
Wingdinger means "sweet!" It's Irish of origin, referring to fairies that flew around with bells and were indentified with good luck. It is widely thought the wingdingers were the inspiration for Disney's Tinkerbell.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.