To 'pull a Hagelmoser' is a (roughly
translated)
traditional, slightly-out-of-fashion German idiom describing a young, dopey person attempting to attend a festivity that already took place a day ago, thus causing amusement witht the
irritated hosts who are suprised by the late arrival.
Fritz,
what are you doing here? Uncle Hubert's divorce dinner-party was
yesterday! You've obviously pulled a Hagelmoser.
Let me check my calendar for your sister's wedding ceremony. I certainly
don't want to pull a Hagelmoser.