If Secret Crush actually needs you to click buttons to invite your friends to add it, the criminal scumbags who designed it have missed a trick; some other applications, such as RockYou's Super Wall and related applications, are able to send messages to randomly selected individuals from a user's friend list, purporting to be that user and asking to be installed to see a message from them, without the user's intervention. (I once found in my notifications the notice that I had messaged three randomly-chosen people, whose relationships to me have nothing in common, inviting them to install Super Wall. Soon after that, Super Wall was no longer installed on my page.)
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