Jet

Jet is a powerful methamphetamine that stimulates the central nervous system. The initial euphoric rush rarely lasts more than a few minutes, but during that time, the user is filled with a rush of energy and strength. The drug was synthesized by Myron, and is extracted from Brahmin dung. The process for manufacturing jet was founded by Myron as he noticed that brahmin farmers were getting "high" with no reason. Further investigations led Myron knowing that the euphoric states experienced by the farmers were due to gas emissions coming from brahmin dung created by a healthy brahmin diet consisting of "magical shrooms". Gaseous emissions from the brahmin, after they were collected, are then further purified and canned, presenting the all clean, odourless Jet. Thanks to Myron and the Jet, the Mordino family built their drug empire.

Inconsistencies
While it is said that Myron created Jet, Mrs. Bishop says that she got hooked on Jet by Bishop (before they got married) and for that she got kicked out of Vault City, which would require Jet to be much older than Myron is. According to Chris Avellone, what Mrs. Bishop says is a mistake and is not canon. It is more likely that Bishop got her hooked on some other drug. Consistent use of Jet will have muddled Mrs. Bishop's perceptions in any case.