Valentine's Day

Valentine's Day is a holiday celebrated on February 14. People celebrate it by buying valentines, bouquets of roses and other flowers, and heart-shaped boxes of candy. Although it rarely happens, some couples have even gotten married on Valentine's Day.
Hanna-Barbera has a couple of cartoons that reference the holiday.
The Flintstones
"The Gravelberry Pie King." In the episode's opening teaser, Fred Flintstone mentions Valentine's Day while he and Barney Rubble are on their way to work.
The Popeye Valentine's Day Special: Sweethearts at Sea
Olive Oyl literally sails out of Popeye's life, and he sets out to bring her back.
The Smurfs
"My Smurfy Valentine."
On Valentine's Day, Smurfette searches for a Prince Smurfing, and Cupid tries to make people and animals fall in love, and even tries his arrows on Grouchy Smurf. Gargamel and Chlorhydris have evil plans for the holiday.