Yma: Wha-a-a? The title piece in this collection of humors is probably one of the funniest shaggy name stories around. It seems that Mr. Meehan had a dream that he hosted a cocktail party Jam packed with celebrities with unusual monosyallabic first names and they insisted on being introduced on a first name basis. Therefore Yma (Sumac), Ava (Gardner) etc. with the introductions getting farther out and the host more miserable with each new arrival. Mr. Meehan is consistently entertaining whether doing a takeoff of Jacqueline Susann or presenting some absolutely brilliant capsulizations of old '30's and '40's movies designed to let the late- late- and later night movie addict get some sleep. Some of the pieces have appeared in The New Yorker and as a whole the collection is a corker.