I am not at home so cannot give exact details but there is a card, an event card which I think is from Age I. It causes one civilization (the weakest) to lose 1 population and 1 civilisation (the strongest) to gain 1 population. We played it that 1 Civ returned a worker to its bank and the other gained a worker from its bank, it could be interpreted that you give the other civilisation a yellow token. However with cards that cause you to do this it is typically said in a way that leaves no room for error.
I was wondering how other ppl have interpreted this card?
edit - Its weakest loses 3 culture and 1 pop and strongest gains 3 culture and 1 pop.
Not only is stated in rules that losing/gaining population or Resources isn't ment to be giving/getting tokens to another player, but there actualy is an Event which specificly tells you to give Yellow token from your bank to enemy's bank.