Agajubu
A nonsense phrase uttered between friends when there's no subject to talk about or to break an awkward silence with a few laughs. Its randomness and absurdity makes it humorous.
Group of friends: *don't know what to say*
One friend: "Agajubu!"
Whole group: *Laughs*
One friend: "Agajubu!"
Whole group: *Laughs*