If you are 18 or over, you're invited to the FUN 107 Monster Mash tonight at White's of Westport.   Over the years we have had some of the best attended, most spectacular Halloween parties the Southcoast has ever seen.  But tonight's will rival the best.   The costumes get better and show more creativity every year.  The dance music is non-stop and the floor will be packed from start to finish.  We have cash costume contests, and live performances by The Portuguese Kids, and the Boston-based national recording group AHMIR.   They have a new hit single called "War".   So put on your best costume, bring your boo or closest friends and come to the favorite Halloween party haunt, Monster Mash.