Speaking of X's, there are various theories about how they came to represent kisses. I like the suggestion that an X looks like a stylized picture of pouting lips meeting. Cute.
More plausibly, X was used in place of a signature by people who couldn't write their names. Sometimes they kissed their signature, perhaps to lend veracity to a contract, like kissing a bible. Hence an X became a kiss by association.
Isn't that interesting.