Akademik

как на иголках
КАК (БУДТО, СЛОВНО, ТОЧНО) НА ИГОЛКАХ coll
[как etc + PrepP; these forms only; subj-compl with быть, сидеть (subj: human)]
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one is in a state of agitation, anxiety, expectation etc:
- X сидит как на иголках{{}} X is on pins and needles;
- X is on tenterhooks;
- [when eagerly anticipating the ending of s.o.'s gripping story, a captivating movie etc] X is on the edge of his seat.

Большой русско-английский фразеологический словарь. — М.: ACT-ПРЕСС КНИГА. . 2004.