RUB has played with regional burgers in the past (recent example: the pimento burger), but tonight and tonight only, we’re told they’ll offer a Jucy Lucy as their Monday special. (You can add this fun one to the off-the-menu items listed in the Post today.) If you grew up in Minneapolis (or watched Adam Richman visit it on Man v. Food), you know the Jucy Lucy is a burger with molten Cheddar cheese in the middle of the patty. It last oozed onto Manhattan menus in a big way when Franklin Becker debuted a version (shown here) at his short-lived Sheridan Square. At $7.50, it’s uncertain whether the RUB version will be as finely wrought as Becker’s (he makes his with a sour-cream spread, as a Behind the Burner demo shows), but does it really need to be?