I know it's nonsensical, but (set! display #f) in a fresh interpreter
causes an infinite loop.

Interrupting with Ctrl+C exits guile.

scheme@(guile-user)> (set! display #f)
While reading expression:
Wrong type to apply: Error while printing exception.
While reading expression:
Wrong type to apply: Error while printing exception.
While reading expression:
Wrong type to apply: Error while printing exception.
While reading expression:
Wrong type to apply: Error while printing exception.
[...]

-- 
bryce