This swap sounds so great! Would it be weird to include rather personal quotes that no one except for one or two persons would get? "Beat Berlin!" would be one for me, that might have some nice possibilities in itself, but would I need to fully explain to everyone? Or if there is one that usually belongs to a comic strip, should the strip be included? I'd pick quotes accordingly of course, there are so many possibilities!
If you have a favorite personal saying or an inside joke or something like that- of course you can include it! And you don't need to explain unless you really want to.
I hope that helps! Let me know if you have any other questions.