My #1 rejected submission to the Hallmark Card folks:

“Whatever you celebrate, unless it’s made-up Kwaanzaa or some religion that commands you to slay your neighbors, I invite you not to pound sand and enjoy merriment with those close to you!”

(A picture of holly and egg nog would accompany the text.)

Rejected submissions #2 and #3 were, admittedly, just long strings of curses. I don’t actually blame Hallmark at all for rejecting them.