Marlon Wayans says black people have a HUGE advantage post-nuclear war. 

We got one of the Bros at LAX Thursday and asked about the booming bomb shelter biz ... and he says he's about to join the rush.

Thing is ... Marlon keys in on a critical issue -- food. If the only food source remaining on earth are rodents, he says black people have skills that white people can't touch. Put differently, fricasseeing a rat blows, but it's a whole different animal with Lawry's and flour.

Fingers crossed we never have to test his theory.