As Peter Pan, Stasha Case sprinkled pixie dust over Theatre in the Park patrons this summer, much to a nephew's delight. But the preferred Case studies are the bimbos, drag kings, and politically incorrect ethnics she's donned in Late Night Theatre shows. Her Hop Sing in Bonanza a couple of years ago was brilliant, and this year's turn in Shoctopussy was no less riotous. David Reed is merely a Bird Boy in the current Late Night show, but his Laura Petrie in Rose Marie's Baby stole the show from a swollen Ron Megee and a blonde Philip blue owl Hooser. With day jobs to support their theater habits, they're troupers in the best sense of the word.