1. Another term for bullshit. The 'wing' comes from trying to 'wing' a comment or statement through without any luck, which comes from 'yuen', an old legendary gambler in ancient China known for his incredibly bad luck.
2. It can also mean someone who constantly bullshits without any luck through over-hyped, often far fetched, distorted statements which is 'winged' through social circles without any regard for his/her personal credibility thus giving other people impressions of him being a constant liar or a person who cannot be trusted.
4. Common fallacy
"Please do not wing yuen
President Bush's accomplishments."
"Never trust a person like Wayne because he is simply a wing yuen
"That play was not even that good. It's just been wing yuened
by that guy over the last couple of days"