L.S./M.F.T.
In the film Blue in the Face, Harvey Keitel and Jim Jarmusch have (to my mind anyway) an extremely interesting conversation about smoking in general and about Lucky Strikes in particular.
In the course of that conversation, Harvey Keitel says when he was a kid the joke used to be that L.S./M.F.T. stood for "Loose Stomach Means Full Toilet."
Frankly, I'm not sure which version I like better.