Tardar Sauce, nicknamed Grumpy Cat, was an American internet celebrity cat. She was known for her permanently "grumpy" facial appearance, which was caused by an underbite and feline dwarfism. She came to prominence when a photograph of her was posted on September 22, 2012, on social news website Reddit by Bryan Bundesen, the brother of her owner Tabatha Bundesen. "Lolcats" and parodies created from the photograph by Reddit users became popular. She was the subject of a popular Internet meme in which humorously negative, cynical images were made from photographs of her.

Resting bitch face (RBF) is a facial expression that unintentionally creates the impression that a person is angry, annoyed, irritated, or contemptuous, particularly when the individual is relaxed, resting, or not expressing any particular emotion. The concept has been studied by psychologists and may have psychological implications related to facial biases, gender stereotypes, human judgement and decision-making. The concept has also been studied by scientists with information technology; using a type of facial recognition system, they found that the phenomenon is real and the condition is as common in males as in females, despite use of the gendered word bitch.