[dontmitch]

Great point. Typing emojis on non-mobile devices is a pain right now. Cmd+Ctrl+Space on Macs brings up an emoji-picker, but I doubt many people know that.

I guess this should be scoped to mobile-only applications. Web services can also use traditional referral links so a memorable referral code isn't as big of a UX win.

[cocotino]

I think the idea is bad overall. Old versions of Android, still widespread, can't enter emoji either.

Best referral code I've seen is a phone number: that way you know it's not going to spread beyond the inner circle of family and friends of the referrer. (Unless you don't want that, of course.)