A pun card? I've made a Christmas card for my niece that is a sea scene because it is a "Christmas Cod"
I'm sending my eldest at university a card of a "HO" to the 3rd power cut in a circle with a Santa hat on it. It is graphic, fun and references all this math classes.
I've made another card for my BIL/SIL that has "HO" "HO" "HO" on the front of it. It is pretty unisex.
Snowman card. There are some fun ones in the gallery - There is even one that seems to be from the top looking down and it is nested circles...