they get DESTROYed
their refcount drops to 0
they get collected
they just refer to something else
they just warn
if they're in an eval
they croak
they form a circular self-reference and so continue to exist forever, but become inaccessible
they shutdown
they are exported
if they are blessed
if they are damned
they reset $self
they go out of scope
they get undefined
they just leave the symbol table
they get dumped and hope someone remembers the reverse
they accidentally get stringified and can't be restored
they're obfuscated and B::Deparse can't handle it
someone enables strict and they have to adapt or leave
they're locals and you move away
they're deprecated for the next release
they just fade to Python
they just hibernate waiting for Perl 6