This expression came from the H-game (PC)/PS2/DC/anime [Kanon]. Ayu Tsukimiya's line (and probably the most famous throughout Kanon). This is her expression when she moans, or whines (like eeeehh, but more original).\r\n\r\nDarn though. She had a sad story. One of my few favorites besides Nayuki.\n> Ayu: I'm cooking cookies.\n> Yuuichi: I bet they'll taste terrible.\n> Ayu: Uguu! I've learned how to bake from Akiko-san!\n> Yuuichi: You can't learn how to bake with just watching in a day..\n> ..although I'll eat them if you manage to make them look good.\n> Ayu: Really?! Then I'll do my best!\n