Not searching for clips because I'm lazy, but England is sexy when he's drunk. France complaining in episode 10 was pretty funny too. And Italy hitting puberty = epic win. *shot by Hetalia haters*
Oh, and the bit in Ouran High School Host Club when Tamaki calls everyone gay.
And not sure if YGOTAS counts, as it is abridged, but BROOKLYN RAGE, BROOKLYN RAAAGE!