Two elves walk into a bar — one’s mad, the other’s rude. They both, by the by, enjoy beer.

What emerges a few years later is not a pile of Christmas toys, but rather a trademark cease-and-desist fight between two of Pennsylvania’s independent breweries.

In one corner, sporting a fur-rimmed red hat and a sack full of goodies, is the face of Troegs Brewing Co.’s Mad Elf Ale.

In the other: the rather crazed-appearing mascot who graces the bottles of Bethlehem Brew Works’ Rude Elf’s Reserve.

The meeting ground for this quarrel is the U.S. Patent and Trademark Office, where Troegs is asking the government to cancel Bethlehem's trademark registration of Rude Elf's Reserve.

Bethlehem didn’t trademark the name until 2006, two years after Troegs’ first trademark on the Mad Elf name appears at the Patent and Trademark Office.

Discovery in the petition began Monday, but according to the trademark office’s website, the legal challenge by Troegs could stretch into next year.

Troegs, whose Mad Elf has become almost ubiquitous around the Christmas season in the midstate, claims that the two elves are likely to cause confusion among beer drinkers.

That’s due, Troegs said, to the "adjective" elf-naming convention — and the fact that in 2010, Bethlehem began expanding the sales of its holiday ale into the same stores as Mad Elf.

Both beers are seasonal, high-alcohol-content holiday drinks and both, of course, feature an elf prominently on the label.

In its response to Troegs’ petition, Bethlehem flatly denies all of the brewery’s allegations.

Jeff Fegley, president and owner of Fegley Brew Works, which owns Bethlehem Brew Works, said in a statement that Troegs was seeking to "monopolize the word ‘elf’ in advertising its beer."

"We do not think the law recognizes such exclusivity," he said.