The restaurant used to be called Rabbit. But in its newest incarnation, Fat Shorty's, rabbit will be paired with rattlesnake and jalapeno in a sausage on the "wildly exotic" section of the German biergarten-style fast-casual restaurant's menu. Fat Shorty's, co-owned by "Hell's Kitchen" winner Rock Harper, opens Thursday, April 4, at 4 p.m.

(Maura Judkis/for The Post (Maura Judkis/for The Post

The Going Out Guide used to think that the Gryphon had the most zoo-like menu in D.C., but Fat Shorty's may be giving it a run for its money: In addition to the rabbit/rattlesnake sausages, there will also be wild boar, alligator andouille, and something called "The Woodsman." Co-owner Aaron Gordon said that he couldn't even remember everything that goes into that sausage: "Venison, antelope and elk" are among the ingredients, he said. "It's all in the deer family."

Fans of Rabbit, the Clarendon salad restaurant, might get whiplash from the restaurant's abrupt leap up the food chain. But Gordon says the difference is mainly in the image the old restaurant's name conjured up.

"We actually had more sandwiches and dinner plates on the menu than salads," he said. "We were serving tons of protein – steaks, tuna – and we were doing sausage sandwiches as part of our specials. It was one of our second or third most popular items."

Thus Fat Shorty's -- the name refers to a childhood nickname, like his Zeke's D.C. Donutz -- was born. There are 21 sausages on the menu (from $6-8), with more typical options like chicken and apple, bratwurst, and pork with beef and cheddar, all sourced from regional providers in Alexandria, Baltimore and Richmond. Each will be served with a choice of two toppings, from the choice of sauerkraut, grilled onions, and hot or sweet peppers, and there will be 10 types of mustard available -- as well as mumbo sauce house-made by D.C. Central Kitchen, where Harper is the director of kitchen operations.

Restaurateur Aaron Gordon (Bonnie Jo Mount/WASHINGTON POST)

Because they serve fries as a side, Gordon said "We have to throw in some ketchup, unfortunately. It’s not supposed to go on sausages, but there are some ketchup fans out there." Other sides will include potato salad and house-made baked beans. Also on the menu: mussels. Said Gordon: "As we all know, sausage and mussels go together perfectly." He'll be doing two types of mussels: One is beer and sausage, and the other is green curry. The nod to Belgium comes through in the restaurant's drink program as well: Of the six beers on tap, half are Belgian and half are German. There are also 20 bottled German and Belgian-inspired beers on the menu, and six wines.

Fat Shorty's will only be open for dinner at first, but will eventually expand to include lunch service. On weeknights, it's open till 11, but on weekends, it will stay open until 2 a.m.

Fat Shorty's, 3035 Clarendon Blvd. Arlington.