IN -- UP TO THE CHIN

{adj. phr.}, {informal} Used also with "ears", "elbows", "eyes" or "knees" instead of "chin", and with a possessive instead of "the". 1. Having a big or important part in; guilty of; not innocent of; deeply in. * /Was Tom mixed up in that trouble last night? He was up to his ears in it./ * /Mr. Johnson is up to the eyes in debt./ * /Mrs. Smith is in debt up to her chin./ Compare: TO THE HILT. 2. Very busy with; working hard at. * /Bob is up to his neck in homework./ * /They are up to their elbows in business before Christmas./ 3. Having very much or many of; flooded with. * /Mary was up to her knees in invitations to go to parties./ Compare: KNEE-DEEP.