I started a company a few years ago called 'Perverted INK', worked out of a bar and sold cards for a quarter on V. day using bar napkins.
It was anything goes.

Men to women-

Roses are red, violets are blue
Come on baby, I got a big stiffy for you.

Flowers are pretty, flowers are sweet,
Rub my belly, you get a pound of meat.

Women to men-

Roses are red, violets are blue,
tonight you can lick me through and through.

Looking at you makes me break into a sweat
Thinking of you, really makes me wet.

Ok I think you get the picture, need I go on? (this is a tamed example!)
Peace. Rustic