This works:
(defun c:OO (/ )
(command "_layer" "_m" "wall" "_c" "161" "" "")
(command "_OFFSET" "L" "C")
(while (= (getvar 'cmdnames) "OFFSET") (command PAUSE)) ; Just needed to add "PAUSE while OFFSET command is active"
(mapcar 'setvar '(clayer cecolor celtype celweight) (list "0" "BYLAYER" "BYLAYER" -1))
(princ)
)