Definitions by Plebe Tribune

smoking lamp 

1. (on sailing ships) a lamp from which a pipe may be lit
2. (figuratively) permission to smoke

"Light smoking lamp" (giving permission for crew to smoke) and "out smoking lamp"
(denying permission) are listed among the 104 bugle calls in the US Navy's "Manual for Buglers", 1953 edition.

smoking lamp by Plebe Tribune March 25, 2009