I just found this easteregg

There's an option in that can be specified be specified in Cargo.toml's [package] called im-a-teapot. If you specify it and try to build the crate, you get

error: failed to parse manifest at `/path/to/Cargo.toml`

Caused by:
  the `im-a-teapot` manifest key is unstable and may not work properly in England

Caused by:
  feature `test-dummy-unstable` is required

  The package requires the Cargo feature called `test-dummy-unstable`, but that feature is not stabilized in this version of Cargo (1.63.0 (fd9c4297c 2022-07-01)).
  Consider trying a newer version of Cargo (this may require the nightly release).
  See https://doc.rust-lang.org/nightly/cargo/reference/unstable.html for more information about the status of this feature.

I don't know why but I find this pretty funny