WordNet
up to your neck
adj. deeply involved; "neck-deep in work"; "up to their necks in debt" [syn: neck-deep, up to my neck, up to her neck, up to his neck, up to our necks, up to their necks]
Usage examples of "up to your neck".
I wish he were here to explain this to you himself, but he's not, and this time you're in them right up to your neck.