Something a person puts out at a bar, party, social etc. It sets the tone for the evening and lets the intended parties know what is going down, (i.e. you're hot, and available). Putting Out The Vibe is done by leaning against the bar, wall, etc and sticking out your ass as much as possible. Seen in Dumb & Dumber by Lloyd Christmas at the Benefit.
(Lloyd begs for Harry to talk to a girl for him.)
Harry Dunne: Ok Ok, stop. What are you gonna do?
Lloyd Christmas: I'm gonna hang by the bar .... Put out the Vibe.
The vibe is a subtle action that people of the gay community will interpret as you being one of their own. It can be an unfortunate outfit, a slight flick of a wrist, or just bad lighting.
"Did you see that sweater vest?? Man, Nick's really putting out the vibe."
"I think I'm going to go for him- sure, he's with that girl, but he's totally putting out the vibe."