Two characters in the comic
Life in Hell by
Matt Groening. They are dressed identically, in vaguely
Charlie Brown-like clothes and
fezzes.
Originally their relationship was rather ambiguous; when asked if they were lovers or brothers, Groening replied, "whatever offends you the most." However, for several years they've been obviously out.
They are still ambiguous about each other, though, and specialize in jokes about passive-aggressive behavior and "family values." They are the protagonists of the funniest cartoon ever.