This is the male equivalent to a baby shower. When the mother of the child has a baby shower, the father of the child has a Diaper Party, at which his buddies (usually the significant others of the women attending the baby shower) bring cases of diapers and beer.

From STEM, an abbreviation short for "Science, Technology, Engineering and Mathematics", a STEMlord is a pejorative term for a particular kind of person who has studied in these areas at university or works in these fields who holds a pretentious, condescending attitude to anyone who has studied in any other fields, particularly the Arts and Humanities. They typically believe themselves to be more "intelligent" and "rational", while generally remaining incredibly ignorant outside of their areas of expertise and having the charisma of a rotting pig's backside.

A party where all the attendees wear diapers and usually use them for their intended purpose

A party for an expecting father. This is typically for males only and is the equivalent of the female only baby shower. The guests bring adult diapers and put them on the soon-to-be father. The father is not allowed to use the bathroom and instead must soil himself in his adult diaper whenever he needs relief. Once the diaper is soiled the guests place the father on the kitchen table and change his diaper.