Once, we were instructed to check out Mount Royal Tavern in the A.M. to see men in suits taking shots before hightailing it to the office. In this spirit, we dutifully reported to the tavern at 8 a.m. one rainy Thursday morn. Alas, it was closed. Put out and thirsty, we pondered: Where to get a breakfast beer? Then, we remembered-Zissimos (1023 W. 36th St.,  467-4707). There we went and were delighted at the healthy tap selection and possibly the loveliest bartender we've encountered in the city: Linda, a petite, stick-thin lady with Coke-bottle spectacles who opens the joint Thursday through Sunday mornings at 6 (the rest of the week, it opens at 9 a.m.). "I'm up anyway," she offered cheerfully. Pawn Stars was on the tube, later Maury. Observing a lone patron toward the back nursing a Bud bottle, pecking at a gambling console, we asked about the morning crowd, and Linda indicated it had slowed down after some inconsistent bartenders overslept their shifts (perhaps disappointed drinkers sought succor at Dimitri's, also open early). After 9:15, the patronage started picking up. We ordered an Irish coffee ($6), which we immediately regretted, because it required Linda to fiddle with the Keurig machine for 10 minutes. The resultant delicious beverage was served in an enormous Zissimos-Ravens glass mug. A jolt of electricity shot through the place when cop cars congregated at Falls Road and the Avenue, near Hampden's methadone clinic; one neighborhood man stormed in the door and hollered to Linda, "What's going on up there?" Linda whipped out a walkie-talkie from behind the bar and went outside with him to investigate. She came back in later, in time to see an Utz deliveryman walk in, head down. "Where have you been!?" she yelled. Apparently, he had taken an unannounced vacation. After placing Zissimos' order-we heard something about pork rinds-Linda called out to him as he left, "Don't make me beat you up now!"