So you're REALLY liking the turtle angle, eh? I'm guessing there must be a reason behind this turtle obsession, but to each their own. And you'd consider going pirate instead of Gothic. You're right, turtles don't normally conjure up scary images unless one has ever latched onto your finger. But, how about if you used a foreign name for turtle, like Tortuga, which really was an infamous island hangout for pirates in the Caribbean that has the shape of a turtle. Your guests would recognize the name Tortuga from the movie Pirates of the Caribbean. Then just add on other words to complete the bar's name (Tortuga Tavern; Tortuga's Castaways; El Tortured Tortuga; Tortuga's Torment; Tortuga's Outcasts; The Terror of Tortuga; etc.). Since pirates would be the theme, you could decorate around that. The sign for the bar could be something like Sickie Ickie showed, or include skulls and crossbones, a pirate wearing a turtle shell for a hat, - lots of options.