Explain xkcd: It's 'cause you're dumb.
Danish is a stick figure character in xkcd. She is very similar in appearance to Megan, but has heavier hair. Personality-wise, she is to Black Hat as Megan is to Cueball.
Like most xkcd characters, her real name is unknown. The name "Danish" is picked from when Black Hat called her "my dearest darling danish", as a term of endearment, in 515: No One Must Know.
A girl that physically looks like Danish appeared in 139: I Have Owned Two Electric Skateboards, long before she was introduced in the Journal series.
Danish is characterized by her cynicism and devilish tricks; and physically by her hair, which is somewhat longer than Megan's.