An adjustment to the expression "You're dead to me," which implies that the target may as well be dead in the speaker's eyes, "You're dude to me" is a statement generally made by men to platonic female friends that the speaker no longer sees as women (and therefore objects of lust). Said mostly in jest or in protest to accusations of hitting on said female friends.

When you eat dirt for the first time and leave your family to build a shack in the woods