Q in the Motif Index stands for Rewards and Punishments. You encounter some fairly common folktale elements in it such as "Q112. - Half of kingdom as reward", or "Q45. - Hospitality rewarded." This section also lists all kinds of horrible executions and punishments (which are also a folklore staple), including:
Q551.1. Undutiful son punished by toad clinging to face
This very popular medieval anecdote, known from French, German, and English sources, tells of a son who is too gluttonous and stingy to share his meal with his own mother or father.
According to the story, the son of a wealth family inherits all his money and properties from his parents - and yet when one of them pays him a visit, the young man hides the meat / roast chicken / other delicacies away in a box, and lies to them, saying he does not have any food to share. After driving the parent away, the son returns to the meal - only to find a toad (or sometimes two toads) sitting on it. The toad launches itself at the son's face and latches on, impossible to remove (and, in some cases, blocking his mouth so he cannot eat). The sinner then goes to the bishop /archbishop / other church person for penance, and is paraded around as a cautionary tale against gluttony and for the importance of filial duties.
TOAD IN THE FACE!
Bring this up to your kids next time they don't want to share the Halloween candy.
Q42.6. Reward for tearing out eye when demanded
Q57.1. Reward for shielding Mary in childbirth from gaze of onlookers
Q88.1. Fra Lippo Lippi is freed by Moors because of his greatness as a painter
Q115.2. King promises daughter she may marry anyone she desires
Q151.2. Death passes by man who fed his stepmother
Q211.7. Punishment for splitting head and eating man‘s brains
Q265.2.1. Blotches on face of satirist (judge) as punishment for wrongful satire (judgment)
Q281.3. Woman eats flesh and leaves cat only bones of fish cat has caught for them. Cursed by cat
Q291.1. St. Peter’s mother dropped from heaven because of hardheartedness
Q415.2. Mice devour hard-hearted man
Q451.0.3. Strong girl breaks impudent suitor‘s right hand and left foot
Q497.1. Moustache pulled out as punishment
Q499.8. Humiliating penance: king to rub nose five times on red hot griddle
Q551.1.1. Betel-nut grows upon a person‘s knee as a punishment
Q551.8.4. Man’s eye bursts forth when he urges saint to marry
Q589.2. Man goes forth naked: cursed with nakedness throughout life