Referring to the character in the film "Top Gun", call sign "Cougar" who completely wimped out after a little dog fighting.
1. To back out of a commitment (pull a cougar)
2. To be scared
3. the anti-wingman
Dude I need a wingman, don't be a coog - - We've had these plans for days, don't coog out on me - - Nah he's not coming on the ride, he pulled a cougar.