  A pebbling move on a graph removes two pebbles at a vertex and adds one
pebble at an adjacent vertex. Rubbling is a version of pebbling where an
additional move is allowed. In this new move, one pebble each is removed at
vertices $v$ and $w$ adjacent to a vertex $u$, and an extra pebble is added at
vertex $u$. A vertex is reachable from a pebble distribution if it is possible
to move a pebble to that vertex using rubbling moves. The optimal rubbling
number is the smallest number $m$ needed to guarantee a pebble distribution of
$m$ pebbles from which any vertex is reachable. We determine the optimal
rubbling number of ladders ($P_n\square P_2$), prisms ($C_n\square P_2$) and
M\"oblus-ladders.
