You can buy them with your phone credit, and in Game, I've seen giftcards to purchase which give you Facebook credits. Click on the Facebook credits token and you'll find out more information.
Tokens are used to play different games on Facebook, and to purchase different things on Facebook.
Games
I believe the tokens you are referring to are all for the application Friends For Sale.
playgame on facebook
How do i get i get free coins on video bingo in games on facebook please help its hard to get any coins thank you
kako da dobije vise tokena
No you don't have to pay to play facebook games. However if you want to but cash or coins on certain games like farmville you will have to pay by direct debit, facebook tokens and so on.
150,000 tokens or 80 playfish cash
There are cards you can buy, like those game cards for like Club Penguin, they should be wherever giftcards are sold.
Yes, playing games on facebook is absolutely free. There is no charge for playing games though some games charge you to buy tokens or power-ups etc. but the games are free.
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Tokens do not have effects, they are Normal Monsters. Even in the case of tokens with inbuilt restrictions such as Sheep Tokens from Scapegoat or other things like the damage from Ojama Tokens, these are lingering effects placed by the card that created the Tokens and not effects of the tokens themselves.