"You are a(n) " + [some usual, boring insulting words]
"You are a dork" ---> lameeeeeee
You can be creative in combining words to the point that the person being insulted won't get what you mean until much later LOL. Plus, you may look soooo intelligent to know words from Elizabethan era!
Remember this was a time when the average person did not read, and other forms of entertainment were not readily available, but good conversation acted as a substitute.
Here it goes :
Just say "Thou art a(n)" + [choose one word from each column]
Example : "Thou art a churlish, dismal-dreaming fustilarian."
Try combining more words from column 1 and column 2 for more interesting insult :
"Thou art an artless, crook-pated, fawning, mewling, elf-skinned puttock."
FEEL FREE !!
Artless Base-court Apple-john Bawdy Bat-fowling Baggage Beslubbering Beef-witted Barnacle Bootless Beetle-headed Bladder Churlish Boil-brained Boar-pig Cockered Clapper-clawed Bugbear Clouted Clay-brained Bum-bailey Craven Common-kissing Canker-blossom Currish Crook-pated Clack-dish Dankish Dismal-dreaming Clot-pole Dissembling Dizzy-eyed Coxcomb Droning Dog-hearted Codpiece Errant Dread-bolted Death-token Fawning Earth-vexing Dewberry Fobbing Elf-skinned Flap-dragon Froward Fat-kidneyed Flax-wench Frothy Fen-sucked Flirt-gill Gleeking Flap-mouthed Foot-licker Goatish Fly-bitten Fustilarian Gorbellied Folly-fallen Giglet Impertinent Fool-born Gudgeon Infectious Full-gorged Haggard Jarring Guts-griping Harpy Loggerheaded Half-faced Hedge-pig Lumpish Hasty-witted Horn-beast Mammering Hedge-born Huggermugger Mangled Hell-hated Jolt-head Mewling Idle-headed Lewdster Paunchy Ill-breeding Lout Pribbling Ill-nurtured Maggot-pie Puking Knotty-pated Malt-worm Puny Milk-livered Mammet Quailing Motley-minded Measle Rank Onion-eyed Minnow Reeky Plume-plucked Miscreant Roguish Pottle-deep Mold-warp Ruttish Pox-marked Mumble-news Saucy Reeling-ripe Nut-hook Spleeny Rough-hewn Pigeon-egg Spongy Rude-growing Pignut Surly Rump-fed Puttock Tottering Shard-borne Pumpion Unmuzzled Sheep-biting Rats-bane Vain Spur-galled Scut Venomed Swag-bellied Skains-mate Villainous Tardy-gaited Strumpet Warped Tickle-brained Varlot Wayward Toad-spotted Vassal Weedy Unchin-snouted Whey-face Yeasty Weather-bitten Wagtail