From Longman Dictionary of Contemporary Englishbe up to your eyebrows in somethingbe up to your eyebrows in somethingspokenBUSY/HAVE A LOT TO DO to have more of something than you can deal with I’m absolutely up to my eyebrows in work. → eyebrow
Examples from the Corpus
be up to your eyebrows in something• Stein is up to his eyebrows in debt. 