Yawning is involuntary opening of the mouth with respiration, breathing first inward, then outward. It is often caused by the power of suggestion. Arousal, attention, personality and intelligence could all be influencing factors  in susceptibility to contagious yawning. A number of studies found that yawns on video played to a classroom for five minutes would induce a responsive yawn in 55% of the audience, but neither videos nor words will work in children below the age of six years. The greater sensitivity to ‘psychological’ yawn stimuli might reflect enhanced self- and social awareness, related to reading ability. It could be mediated by specific brain cells called “mirror neurons” that allow to learn and empathize

if yawning is accompanied by other common anxiety symptoms, it may be due to an anxiety disorder. It is also associated with tiredness, sleepiness, stress and hunger. According to one theory, bored or tired individuals don't breathe as deeply as usual, taking in less oxygen and yawning helps to compensate for it.

Excessive yawning is yawning that occurs frequently (1 to 4 yawns per minute over an extended period of time), sometimes without any apparent reason. Increased yawning often precedes seizures and migraine headaches, in people with epilepsy and migraines. Yawning excessively may also occur in the presence of a heart defect or disease. 

​Yellow discoloration of the skin, especially on the palms and the soles. Could be because of beta-carotene in diet or elevated bilirubin in blood.  

Bilirubin is an orange-yellow pigment formed in the liver by the breakdown of hemoglobin and excreted in bile.
Yellowish discoloration of the skin. mucous membranes and whites of the eyes caused by bilirubin is called Jaundice or icterus. Excess of the pigment bilirubin (hyperbillirubine) is typically caused by obstruction of the bile duct, by liver disease, or by excessive breakdown of red blood cells.

For Jaundiced babies, their face observed in a good light (or after touching and releasing) looks yellow and this discoloration moves downwards to the chest, tummy, arms and legs as the bilirubin increases. The whites of the eyes will also appear yellowed but the skin in the mouth will be healthy pink. Other early symptoms are tiredness, poor feeding and a high-pitch cry.

Hepatitis A signs and symptoms, which typically don't appear until a few weeks after infection with the virus, may include Jaundice, dark yellow urine and clay-colored bowel movements
Early symptoms of Hepatitis C include yellowing skin and mild fatigue, 

Eating too many yellow fruit, vegetables and spices such as carrots, pumpkin or cinnamon could lead to accumulation of beta carotene in the skin, condition  known as ‘carotenodermia’. Usually orange or yellowish tinted skin is only a cosmetic concern, however, very rarely it can be a sign of a slow thyroid, kidney or liver issue.  Some studies have also indicated that very high intake of beta-carotene in heavy smokers may lead to lung cancer.

semisolid custard-like sourish food prepared from milk fermented by added bacteria,  especially Lactobacillus bulgaricus and Streptococcus thermophilus, often sweetened or flavored.
Yoghourt was the preferred English spelling from outside North America before 2000, later replaced by Yoghurt.  Yogurt is preferred in American and Canadian English.
Matsoni, matzoon, matsoon, matsoun, matzoun, madzoon, madzoun macun, matson are types of yogurt of Caucasian cuisine.
Labneh is a strained yogurt, popular in Middle Eastern countries. 
Lassi is a traditional cold yogurt beverage from India and Pakistan. 
Chaas or Mahi is a buttermilk-based drink containing raw milk, cream or yogurt. 
Kefir (Russian, possible of North caucasian origin or from Turkish word meaning "feeling good"), Clabber, Dickmilch (thick milk), and Scandinavian Filbunke. are forms of naturally fermented milk.
Filmjölk (also known as fil) is a Nordic dairy product made from soured milk.
Amasi is an African yogurt with a mild, almost cheesy flavor. Its main cultures are Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris
Dadiah/Dadih, from Indonesia, is made by letting unpasteurized buffalo milk fermented at room temperature in a bamboo tube capped by a banana leaf.
Mishti dahi is an East Indian dessert made by fermenting prepared milk and sugar into thick yogurt. 
Tzatziki is a yogurt sauce made with strained yogurt and grated cucumber, olive oil, salt, and mashed garlic. Mast Va Khiar (Persian yogurt and cucumbers) is a tasty dip originating from Iran. 
Shrikhand is a Middle Eastern yogurt dessert using nuts, raisins, and spices like cardamom and nutmeg.