Something that looks or sound inappropriate. It can also mean something that something is obvious or stupid. Also happens to be Santana(the greatest character ever)'s catch phrase.
Example 1:
Carl-"You guys have a hole to fill and i'm just trying to help will it"
Santana-"Wanky"
Emma-"Santana!"
Example 2:
Kitty- "You're so funny and self deprecating, we're so much alike"
Quinn- Looks around in confusion
Santana- "Wanky"
Example 3:
Puck- "Once you see a baby come out of a girls magic garden everything else is easily acceptable"
Quinn-"I think I love you puck. And I know it's not gonna be easy what, with me and you being me and you. But, i'd rather do
hard with you than easy with someone else."
Santana- "Wanky"
Quinn- "Santana for once i'd appreciate it if you kept you inevitable snark to yourself.
The post effect of not having a wank, when you've turned your computer off and got into bed thinking "I don't need a wank tonight" but you get into bed, get a stonker, and realise you do.