Hi John,

There are a number of passages in the Tipi.taka similar to "one's head
would explode". Typically, the Pali for this reads: "muddhaapi tassa
vipateyya" (his head would split asunder). According to a quick CSCD
search the phrase occurs 23 times in the Suttantapi.taka--mostly in
the Diighanikaaya (18 times). I couldn't tell you if any of them are
related to the four imponderables though, sorry.

Best wishes,
Jim

> This came up in a discussion with some friends and we seem to
> remember somewhere it being said that "one's head would explode",
> but can't remember where. Is there somewhere else in the canon
> where these imponderables are discussed more graphically?
>
> John