Crepitus was allegedly the Roman god of flatulence. He was usually depicted as a young child farting.
However, he's only allegedly so because there's controversy about whether the Romans recognized such a god, or whether Crepitus was the creation of early Christians trying to satirize pagan beliefs.
According to Wikipedia, there are references to Crepitus in ancient texts, but only in Christian works, not pagan ones.

image source: POOP Project
Twitch divination (also known as palmomancy) was the ancient art of divining the future by interpreting body tremors, tics, and twitches.
According to the Faces and Voices blog, few manuals of palmomancy survive from ancient times. But the few that do offer some interesting advice. For instance, from a treatise preserved at Manchester's John Rylands Library:
‘If the anus, that some also call ‘ring’, twitches, it shows inspections, abuses, and the discovery of secret matters’.
And what does it mean if your buttock twitches? The answer from
Omens and Oracles: Divination in Ancient Greece by Matthew Dillon:
Two surviving texts attributed to the legendary diviner Melampous deal with divination: On Divination by Twitchings (Peri Palmon Mantike) and On [Divination from] Birthmarks (Peri Elation tou Somatos)... Both of these texts are very neglected, with no English translation of either in print...
Melampous' Twitchings covers some 187 cases. Involuntary twitchings of the body were easily interpreted as ominous by those who experienced them, and this handy guidebook provided instant advice to the reader as to their meaning... Dating to the third century AD, the earliest papyrus begins with the entry:
[A twitching of] the left buttock means joy: for the slave, something beneficial; for the virgin, blame will fall on the widow for strife [this is somewhat difficult to understand; there may be an allusion here the reader would have recognised]; for the soldier, promotion.
This is in fact a more elaborate version of two short entries in Melampous' Twitchings, which indicate that twitching of either buttock means prosperity.
Nov 1971: Nine-year-old Fiona Gordon realized that the supposedly ancient Roman coin on display at the
South Shields Museum was actually a promotional replica given away by a soft drinks company, Robinsons.

Newport News Daily Press - Nov 3, 1971
I'm pretty sure that the coin below is similar (if not identical) to the one that was on display at the museum. In 1971, Robinsons sent these coins to anyone who mailed in enough bottle caps. (Source:
CoinCommunity.com)
Some ancient weirdness: The First Council of Nicaea, in 325 AD, was a meeting of Christian bishops in which they tried to establish the rules and doctrines that all Christians were supposed to follow.
Wikipedia says:
Its main accomplishments were settlement of the Christological issue of the divine nature of God the Son and his relationship to God the Father, the construction of the first part of the Nicene Creed, mandating uniform observance of the date of Easter, and promulgation of early canon law.
However, one of the lesser-known rules that the bishops enacted at the Council was to ban men who had castrated themselves from being in the clergy. Because, apparently, self-castration had become something of a fad among early Christians. Enough so that the bishops felt the need to put an official stop to the practice.
The historian Daniel Caner has examined this issue in his 1997 article
"The practice and prohibition of self-castration in early Christianity".
Caner notes that the fad had its origin in a passage from the New Testament, Matthew 19:12, in which Jesus appears to endorse the practice of self-castration. As the passage reads in the King James translation:
For there are some eunuchs, which were so born from their mother’s womb; and there are some eunuchs, which were made eunuchs of men; and there be eunuchs, which have made themselves eunuchs for the kingdom of heaven’s sake. He that is able to receive it, let him receive it.
Most interpreters of the Bible, ancient and modern, argue that when Jesus used the word 'eunuch' he meant it as a synonym for 'celibacy'. Apparently this was a common use of the term 'eunuch' in the ancient world.
Nevertheless, he used the term eunuch. So some early Christians decided the passage should be taken literally. In which case, Jesus seemed to be saying that, while self-castration was not appropriate for all men, for an elite few it was an ideal to strive for. Inspired by this passage, a number of men "took the sickle and cut off [their] private parts."
The most prominent Church father who was said to have castrated himself was
Origen of Alexandria (c. 185 - c. 253). But Caner notes that there was an entire sect of early Christians, the Valesians, who embraced the practice.
Wikipedia says that, in addition to castrating themselves, "They were notorious for forcibly castrating travelers whom they encountered and guests who visited them."
According to Caner, the more widely adopted Christianity became in the Roman empire, the more the Church tried to present itself as the upholder of mainstream values, and self-castration really didn't fit into that image. Therefore, "Radical manifestations of an ideal de-sexualization... became a 'heretical' threat to the orthodox community."
Strange job title. 'Shepherd of the Royal Anus' (neru pehut) was a title held by several court physicians in Ancient Egypt, including Ir-en-akhty (who lived during the
First Intermediate Period) and his predecessor Khuy. It could also be translated as 'Herdsman of the Anus' or 'Guardian of the Anus'.
Here's a partial explanation:
As in all ancient cultures, the doctor was part of the priesthood. Each physician was responsible for curing only one illness. The god-king was attended to by a host of medical practitioners, each specializing in one body part and bearing such titles as Royal Keeper of the Pharaoh's Left Eye, Royal Keeper of the Pharaoh's Right Eye, or Shepherd of the Royal Anus.
And more:
[Neru Pehut was] a title borne by physicians qualified to prescribe and administer medicines rectally. Herodotus frequently speaks of the alimentary canal: the Egyptians, he says, 'purge themselves, for their health's sake, with emetics and clysters." Diodorus Siculus, writing four hundred years later, echoes this observation, saying that 'in order to prevent sicknesses they look after the health of their bodies by means of drenches, fastings, and emetics.' Enemas were among the most common modes of treatment, employed several times a month for preventive purposes.