How to transfer GeekBux?

I've promised to send some GeekBux to one of the users, but i can't find this option anywhere... any clues on where is it?

I know it was possible at some point. Is it still doable?

Should i open this thread in the "Geek Help Desk" category? I am not sure whether this category is proper for this thread.

Go in the game room and hit "transfer cash"

Thanks! Much appreciated.